Detection and quantification of AKT-mTOR pathway proteins

Information

  • Patent Grant
  • 11561226
  • Patent Number
    11,561,226
  • Date Filed
    Monday, March 13, 2017
    7 years ago
  • Date Issued
    Tuesday, January 24, 2023
    a year ago
Abstract
This disclosure relates to the field of mass spectrometry analysis. In some embodiments, the disclosure relates to compositions and methods for detecting and quantifying proteins in the AKT-mTOR pathway by immunoprecipitation enrichment followed by mass spectrometry analysis.
Description
SEQUENCE LISTING

The instant application contains a sequence listing which has been submitted electronically in ASCI format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Aug. 27, 2018, is named LT01152US SL.txt and is 154,793 bytes in size.


FIELD OF INVENTION

This disclosure relates to the field of detection and quantification of AKT-mTOR pathway proteins, including phosphorylated proteins, by immunoprecipitation and mass spectrometry.


BACKGROUND

The AKT-mTOR pathway plays a central role in tumor progression and anti-cancer drug resistance. The quantitative measurement of protein expression and post-translational modifications of the AKT-mTOR pathway is necessary for precisely characterizing cancer, monitoring cancer progression, and determining treatment responses. See Logue, J. S.; Morrison, D. K.; Genes Dev. Apr. 1 2012, 26 (7), 641-50.


A major limitation in the detection and quantitation of AKT-mTOR pathway proteins is the lack of rigorously validated methods and reagents. Currently, only semi-quantitative results from Western blotting, ELISA, and Luminex assays are available. Mass spectrometry (MS) is increasingly becoming the detection methodology of choice for assaying protein abundance and post-translational modifications. However, to date, MS has not been successful in quantifying AKT-mTOR pathway proteins, possibly due to their low abundance and significant post-translational modification profiles.


Immunoprecipitation (IP) is commonly used upstream of MS as an enrichment tool for low-abundant protein targets. See, Gingras et al., Nat. Rev. Mol. Cell. Biol., Aug. 2007, 8 (8), 645-54; and Carr, S. A. et al., Mol. Cell. Proteomics Mar. 2014, 13 (3), 907-17. The identification of appropriate antibodies for use in IP upstream of MS is important, as not all antibodies that bind to protein will be effective immunoprecipitation tools, and further, not all antibodies that are effective immunoprecipiation tools will lead to successful identification via MS.


SUMMARY OF INVENTION

The present disclosure provides reagents and methods for detecting and quantifying AKT-mTOR pathway proteins via immunoprecipitation (IP), mass spectrometry (MS), and immunoprecipitation followed by mass spectrometry (IP-MS).


In some embodiments, methods for immunoprecipitating an AKT-mTOR pathway protein (target protein) are provided, comprising contacting a biological sample with any one of the antibodies recited in Table 1. In some embodiments, the antibodies useful in the IP methods comprise the antibodies recited in Table 8. In some embodiments, the antibodies useful in the IP methods comprise the antibodies recited in Table 9. The methods may comprise washing the contacted biological sample to enrich for antibody-protein conjugates. Further methods include detecting the antibody-protein conjugates (the immunoprecipitated target protein) to determine the AKT-mTOR pathway protein in the biological sample. In some embodiments, the antibody is labelled. In some embodiments, a detection reagent is provided to the enriched antibody-protein conjugate. In some embodiments the label is biotin and the detection reagent is streptavidin.


In some embodiments the IP is single-plex. In some embodiments the IP is multi-plex. The antibodies useful in multi-plex IP may comprise the antibodies of Table 8 and Table 9.


In some embodiments a method for detecting AKT-mTOR pathway proteins via MS is provided, comprising isolating proteins from a biological sample, digesting the isolated proteins, assaying the digested proteins via mass spectrometry to determine the presence of a peptide for AKT-mTOR pathway protein(s), and determining the identity of one or more AKT-mTOR pathway protein(s) in the sample. In some embodiments, the peptide for AKT-mTOR pathway protein(s) comprises a sequence of SEQ ID NO: 1-SEQ ID NO: 424. In some embodiments the peptide is less than 40 amino acids in length. In some embodiments, the peptide for AKT-mTOR pathway protein(s) consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424.


In some embodiments a method for quantifying AKT-mTOR pathway proteins via MS is provided, comprising isolating proteins from a biological sample, digesting the isolated proteins, assaying the digested proteins via mass spectrometry to determine the presence of a peptide for AKT-mTOR pathway protein(s), and determining the quantity of one or more AKT-mTOR pathway protein(s) in the sample. In some embodiments, the peptide for AKT-mTOR pathway protein(s) comprises a sequence of SEQ ID NO: 1-SEQ ID NO: 424. In some embodiments the peptide is less than 40 amino acids in length. In some embodiments, the peptide for AKT-mTOR pathway protein(s) consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments a method for detecting AKT-mTOR pathway proteins via IP-MS is provided, comprising treating a biological sample with at least one antibody capable of immunoprecipitating AKT-mTOR target pathway protein(s) from a biological sample, digesting the isolated proteins, assaying the digested proteins via mass spectrometry to determine the presence of a peptide for AKT-mTOR pathway protein(s), and determining the identity of one or more AKT-mTOR pathway protein(s) in the sample. In some embodiments, the peptide for AKT-mTOR pathway protein(s) comprises a sequence of SEQ ID NO: 1-SEQ ID NO: 424. In some embodiments the peptide is less than 40 amino acids in length. In some embodiments, the peptide for AKT-mTOR pathway protein(s) consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments a method for quantifying AKT-mTOR pathway proteins via IP-MS is provided, comprising treating a biological sample with at least one antibody capable of immunoprecipitating AKT-mTOR target pathway protein(s) from a biological sample, digesting the isolated proteins, assaying the digested proteins via mass spectrometry to determine the presence of a peptide for AKT-mTOR pathway protein(s), and determining the quantity of one or more AKT-mTOR pathway protein(s) in the sample. In some embodiments, the peptide for AKT-mTOR pathway protein(s) comprises a sequence of SEQ ID NO: 1-SEQ ID NO: 424. In some embodiments the peptide is less than 40 amino acids in length. In some embodiments, the peptide for AKT-mTOR pathway protein(s) consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments the AKT-mTOR pathway target protein is phosphorylated.


Methods for determining the ratio of phosphorylated to non-phosphorylated AKT-mTOR pathway proteins are provided, comprising any of the above IP, MS, or MS-IP methods, wherein a further step of determining the ratio of phosphorylated to non-phosphorylated protein is provided. In some embodiments, the method is an MS-IP method comprising treating a biological sample with one or more antibodies capable of immunoprecipitating one or more phosphorylated AKT-mTOR pathway proteins, and separately treating the same biological sample with one or more antibodies capable of immunoprecipitating at least one or more of the same or different non-phosphorylated AKT-mTOR pathway proteins; digesting the immunoprecipitated AKT-mTOR pathway proteins; adding a first and a second detectably labelled internal standard peptide of known amount to the digested proteins, wherein the first internal standard peptide has the same amino acid sequence as a phosphorylated AKT-mTOR pathway peptide used to identify the phosphorylated protein, and the second internal standard peptide has the same amino acid sequence as the non-phosphorylated AKT-mTOR pathway peptide used to identify the non-phosphorylated protein; assaying the digested protein and internal standards via mass spectrometry to determine the presence and amount of phosphorylated and non-phosphorylated AKT-mTOR pathway proteins, wherein the AKT-mTOR pathway peptide comprises a peptide of SEQ ID NO: 1-SEQ ID NO: 424, and is less than 40 amino acids in length; determining the quantity of AKT-mTOR phosphorylated and non-phosphorylated pathway proteins in the sample, and determining the ratio of phosphorylated to non-phosphorylated pathway proteins. In some embodiments, the peptide for AKT-mTOR pathway protein(s) consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments, the biological sample is human. In some embodiments, the biological sample is non-human. In some embodiments, the biological sample is mammalian. In some embodiments, the biological sample is from rat, mouse, guinea pig, hamster, cow, pig, horse, goat, sheep, dog, cat, or non-human primate.


In embodiments utilizing an AKT-mTOR pathway peptide, the peptide may be modified with a detectable label. The detectable label may comprise an isotope, such as a heavy isotope, such as those known to those of skill in the art, including 13C, 15N, 2H and 180. In some embodiments, the modified/labelled peptide comprises a peptide of SEQ ID NO: 213-424. In some embodiments the peptide is less than 40 amino acids in length. In some embodiments the modified/labelled peptide consists of a peptide of SEQ ID NO: 213-424. In some embodiments the modified/labelled peptide consists of a peptide of SEQ ID NO: 213-424, wherein the peptide is further modified.


In some embodiments, the antibody for IP is selected from the group consisting of the antibodies recited in Table 1. In some embodiments, the antibody for IP is an antibody having the six CDRs of any of the antibodies of Table 1. The antibody may be capable of immunoprecipitating more than one AKT-mTOR pathway protein. In some embodiments the antibody is labelled or capable of being labelled. The label may be any label known to those of skill in the art including enzymatic and fluorescent labels, such as biotin. In some embodiments more than one antibody is used in a multi-plex IP. In some embodiments, the multi-plex IP comprises the antibodies of Table 8. In some embodiments, the multi-plex IP comprises the antibodies of Table 9.


In some embodiments, two or more antibodies are utilized to analyze one biological sample. For example, a first antibody is capable of immunoprecipitating a phosphorylated AKT-mTOR pathway protein, and a second antibody is capable of immunoprecipitating a non-phosphorylated version of the AKT-mTOR pathway protein precipitated by the first antibody. In some embodiments, a single antibody is capable of immunoprecipitating a phosphorylated and non-phosphorylated AKT-mTOR pathway protein.


In some embodiments, the immunoprecipitation comprises treating a sample with a labelled antibody capable of binding to an AKT-mTOR pathway protein to provide a labelled antibody-protein conjugate. The method may further comprise contacting the labelled antibody-protein conjugate with a capture agent capable of binding to the labelled antibody to isolate the pathway protein from the sample. The label may be biotin and the capture agent may be streptavidin.


The quantity of an AKT-mTOR pathway protein may be determined by adding an internal standard peptide of known amount to the digested protein prior to mass spectrometry. In some embodiments, the internal standard peptide has the same amino acid sequence as the AKT-mTOR pathway peptide. In some embodiments, the internal standard is detectably labeled. The method may further comprises determining the quantity of an AKT-mTOR pathway peptide by comparison to the internal standard.


In some embodiments, the internal standard peptide comprises a sequence of SEQ ID NO: 1-SEQ ID NO: 424. In some embodiments the peptide is less than 40 amino acids in length. In some embodiments, the peptide consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments, quantifying the AKT-mTOR pathway protein comprises comparing an amount of an AKT-mTOR pathway peptide in the sample to an amount of the same AKT-mTOR pathway peptide in a control sample.


Quantifying an AKT-mTOR pathway protein may comprise comparing an amount of an AKT-mTOR pathway peptide to an internal standard peptide of known amount, wherein both the peptide in the biological sample and the internal standard peptide comprise SEQ ID NO: 1-SEQ ID NO: 424, wherein the standard peptide is detectably labeled, and wherein the peptide is less than 40 amino acids long. In some embodiments, the standard peptide consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments the mass spectrometry is selected from tandem mass spectrometry and discovery mass spectrometry. The targeted mass spectrometry may be selected from multiple reaction monitoring (MRM), selected reaction monitoring (SRM), and parallel reaction monitoring (PRM), or combinations thereof.


In some embodiments the biological sample is selected from isolated human cells, plasma, serum, whole blood, CSF, urine, sputum, tissue, and tumorous tissue.


In some embodiments, the method further comprises quantifying the relative amount of AKT-mTOR pathway protein. In some embodiments, the method further comprises quantifying the absolute amount of AKT-mTOR pathway protein.


In some embodiments, the digesting comprises a protease or chemical digest. In some embodiments the digestion may be single or sequential. The protease digestion may comprise trypsin, chymotrypsin, AspN, GluC, LysC, LysN, ArgC, proteinase K, pepsin, clostripain, elastase, GluC biocarb, LysC/P, LysN promisc, protein endopeptidase, staph protease or thermolysin.


The chemical cleavage may comprise CNBr, iodosobenzoate or formic acid.


In some embodiments the digestion is a protease digest with trypsin.


In some embodiments the methods further comprise desalting after digestion and prior to mass spectrometry.


The AKT-mTOR pathway protein may be selected from AKT1 (UniProtKB—P31749), AKT2 (UniProtKB—P31751), IR (also known as INSR) (UniProtKB P06213), IGF1R (UniProtKB—P08069), IRS1 (UniProtKB—P35568), TSC2 (UniProtKB—P49815), mTOR (UniProtKB—P42345), GSK3a (UniProtKB—P49840), GSK3b (UniProtKB—P49841), GSK3a/GSK3b, p70S6K (also known as RPS6KB1) (UniProtKB—P23443), RPS6 (UniProtKB—P62753), PRAS40 (also known as AKT1S1) (UniProtKB—Q96B36), and PTEN (UniProtKB—P60484).


In some embodiments, the AKT-mTOR pathway is a protein that interacts with any of AKT1 (UniProtKB—P31749), AKT2 (UniProtKB—P31751), IR (also known as INSR) (UniProtKB P06213), IGF1R (UniProtKB—P08069), IRS1 (UniProtKB—P35568), TSC2 (UniProtKB—P49815), mTOR (UniProtKB—P42345), GSK3a (UniProtKB—P49840), GSK3b (UniProtKB—P49841), GSK3a/GSK3b, p70S6K (also known as RPS6KB1) (UniProtKB—P23443), RPS6 (UniProtKB—P62753), PRAS40 (also known as AKT1S1) (UniProtKB—Q96B36), and PTEN (UniProtKB—P60484).


In some embodiments, the AKT-mTOR pathway protein is phosphorylated.


In some embodiments, the concentration of AKT-mTOR protein that may be detected ranges from about 0.08 fmol to about 2000 fmol.


In some embodiments, the lower limit of detection is about 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, or 0.25 fmol. The lower limit of detection may be within the range of about 0.05-0.25 fmol.


In some embodiments the lower limit of quantification is about 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, or 0.75 fmol. The lower limit of quantification may be within the range of about 0.05-0.75 fmol.


Kits comprising one or more antibodies capable of immunoprecipitating an AKT-mTOR pathway protein are encompassed.


Kits comprising one or more antibodies capable of immunoprecipitating an AKT-mTOR pathway protein, and reagents useful for performing mass spectrometry to detect an AKT-mTOR pathway protein are also provided.


Also encompassed are kits comprising one or more antibodies capable of immunoprecipitating an AKT-mTOR pathway target protein, and reagents useful for performing mass spectrometry to quantify an AKT-mTOR pathway protein.


The antibody to be included in the kit may be selected from any one or more of the antibodies recited in Table 1. In some embodiments the antibody is labelled or capable of being labelled. The label may be any label known to those of skill in the art including enzymatic and fluorescent labels, such as biotin. In some embodiments, the kit comprises more than one antibody. In some embodiments, the kit comprises two or more of the antibodies selected from the antibodies recited in Table 8. In some embodiments, the kit comprises two or more of the antibodies selected from the antibodies recited in Table 9. In some embodiments, the kit comprises two or more of the antibodies selected from the antibodies recited in Table 8 and two or more of the antibodies selected from the antibodies recited in Table 9. In some embodiments, the kit comprises each of the antibodies recited in Table 8, Table 9, or Tables 8 and 9.


The kits may further comprise an AKT-mTOR pathway peptide. In some embodiments, the peptide comprises a sequence of SEQ ID NO: 1-SEQ ID NO: 424. In some embodiments, the peptide is less than 40 amino acids in length. In some embodiments, the peptide consists of a sequence of SEQ ID NO: 1-SEQ ID NO: 424. The peptides of SEQ ID NO: 1-SEQ ID NO: 212 may be labelled. In some embodiments, the label on SEQ ID NO: 1-SEQ ID NO: 212 differs from the label shown on the peptides of SEQ ID NO: 213-SEQ ID NO: 424. In some embodiments, the peptide comprises or consists of a peptide selected from the peptides shown in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204).


In some embodiments, the kit may comprise at least one peptide selected from peptides of SEQ ID NO: 213-SEQ ID NO: 424, wherein the peptide is less than or equal to 40 amino acids. In one embodiment, the kit comprises at least one peptide consisting of the peptides of SEQ ID NO: 213-SEQ ID NO: 424.


The peptides provided in the kit may be detectably labeled or capable of being modified to be detectably labeled. In some embodiments, the kit may comprise at least one peptide selected from peptides of SEQ ID NO: 1-SEQ ID NO: 212, wherein the peptide is detectably labeled or capable of being modified to be detectably labeled.


In some embodiments, the kit further comprises a protease or chemical agent capable of digesting an immunoprecipitated protein sample. The protease agent may be trypsin, chymotrypsin, AspN, OluC, Lyse, LysN, ArgC, proteinase K, pepsin, clostripain, elastase, GluC biocarb, LysC/P, LysN promisc, protein endopeptidase, Staph protease or thermolysin. The chemical agent may be CNBr, iodosobenzoate or formic acid.


The kits may be utilized to detect AKT-mTOR pathway proteins, including AKT1 (UniProtKB—P31749); AKT2 (UniProtKB—P31751), IR (also known as INSR) (UniProtKB P06213), IGF1R (UniProtKB—P08069), IRS1 (UniProtKB—P35568), TSC2 (UniProtKB—P49815), mTOR (UniProtKB—P42345), GSK3a (UniProtKB—P49840), GSK3b (UniProtKB—P49841), GSK3a/GSK3b, p70S6K (also known as RPS6KB1) (UniProtKB—P23443 (KS6B1_HUMAN)), RPS6 (UniProtKB—P62753), PRAS40 (also known as AKT1S1)(UniProtKB—Q96B36), and PTEN (UniProtKB—P60484).


The AKT-mTOR protein to be detected and quantified by the kits may be phosphorylated.


Also encompassed are antibodies recited in Table 1 for use in immunoprecipitating an AKT-mTOR pathway protein. The antibody may be used in methods comprising immunoprecipitating an AKT-mTOR pathway protein prior to analyzing the protein via mass spectrometry.


AKT-mTOR pathway peptides selected from the peptides of Table 3 are encompassed. The AKT-mTOR pathway peptides may be used in methods of detecting and quantifying AKT-mTOR pathway proteins in biological samples. The AKT-mTOR pathway peptides may be used in methods comprising immunoprecipitating the AKT-mTOR pathway protein from the biological sample, and analyzing the immunoprecipitated protein via mass spectrometry.





BRIEF DESCRIPTION OF DRAWINGS


FIG. 1 shows a schematic of the AKT-mTOR pathway proteins.



FIG. 2 shows one representative workflow for an immunoprecipitation-enriched mass spectrometry assay to identify AKT-mTOR pathway proteins.



FIG. 3 shows results from an experiment to enrich for low abundant AKT-mTOR pathway proteins from A549 cells.



FIG. 4 shows detection and quantitation limits of peptides for 12 AKT-mTOR pathway proteins.



FIG. 5 shows the results of a multiplex immunoprecipitation plus nanoLC-MS/MS assay for 10 phosphorylated and 11 total AKT-mTOR pathway proteins.



FIG. 6 shows representative results from a multiplex immunoprecipitation plus nanoLC-PRM/MS assay AKT-mTOR pathway proteins. Darker gray bars are A549 cells, and lighter gray bars are HCT116 cells.



FIGS. 7A, 7B, 7C, 7D, 7E, 7F, 7G, and 7H show a comparison of various methods to detect AKT-mTOR pathway proteins, including Luminex, ELISA, Western Blot, and the IP-Mass spec assay in IGF stimulated (dark gray) and (non-stimulated (light gray) cells.



FIG. 8 shows a summary of AKT-mTOR pathway proteins identified and quantified in two different cell lines, with and without immunoprecipitation enrichment, using the mass spec methods.



FIG. 9 shows technology correlation for total AKT-mTOR pathway targets.



FIG. 10 shows technology correlation for phopho-AKT-mTOR pathway targets.



FIG. 11 shows IP to Western Blot validation of AKT-mTOR pathway targets.





DESCRIPTION OF THE EMBODIMENTS

This description and exemplary embodiments should not be taken as limiting. For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages, or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about,” to the extent they are not already so modified. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.


It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.


As used herein, an “AKT-mTOR pathway protein” includes, but is not limited to, AKT1 (UniProtKB—P31749), AKT2 (UniProtKB—P31751), IR (also known as INSR) (UniProtKB P06213), IGF1R (UniProtKB—P08069), IRS1 (UniProtKB—P35568), TSC2 (UniProtKB—P49815), mTOR (UniProtKB—P42345), GSK3a (UniProtKB—P49840), GSK3b (UniProtKB—P49841), GSK3a/GSK3b, p70S6K (also known as RPS6KB1) (UniProtKB—P23443), RPS6 (UniProtKB—P62753), PRAS40 (also known as AKT1S1) (UniProtKB—Q96B36), and PTEN (UniProtKB—P60484).


As used herein “protein”, “peptide”, and “polypeptide” are used interchangeably throughout to mean a chain of amino acids wherein each amino acid is connected to the next by a peptide bond. In some embodiments, when a chain of amino acids consists of about two to forty amino acids, the term “peptide” is used. However, the term “peptide” should not be considered limiting unless expressly indicated.


The term “antibody” is used in the broadest sense and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies, multispecific antibodies (such as bispecific antibodies), and antibody fragments so long as they exhibit the desired immunoprecipitating activity. As such, the term antibody includes, but is not limited to, fragments that are capable of binding to an antigen, such as Fv, single-chain Fv (scFv), Fab, Fab′, di-scFv, sdAb (single domain antibody) and (Fab′)2 (including a chemically linked F(ab′)2). Papain digestion of antibodies produces two identical antigen-binding fragments, called “Fab” fragments, each with a single antigen-binding site, and a residual “Fc” fragment. Pepsin treatment yields a F(ab′)2 fragment that has two antigen-binding sites. The term antibody also includes, but is not limited to, chimeric antibodies, humanized antibodies, and antibodies of various species such as mouse, goat, horse, sheep, chicken, etc. Furthermore, for all antibody constructs provided herein, variants having the sequences from other organisms are also contemplated, such as CDR-grafted antibodies or chimeric antibodies. Antibody fragments also include either orientation of single chain scFvs, tandem di-scFv, diabodies, tandem tri-sdcFv, minibodies, etc. Antibody fragments also include nanobodies (sdAb, an antibody having a single, monomeric domain, such as a pair of variable domains of heavy chains, without a light chain). An antibody fragment can be referred to as being a specific species in some embodiments (for example, human scFv or a mouse scFv). This denotes the sequences of at least part of the non-CDR regions, rather than the source of the construct. The antibodies provided herein are referred to by reference to name and catalog reference. The skilled artisan, holding this name and catalog information, is capable of determining the sequence of the antibody, and therefore the disclosure encompasses any antibody having at least partial sequence of a reference antibody so long as the antibody maintains its ability to immunoprecipitate its antigen protein. In some embodiments, the antibodies comprise antibodies having the same CDRs as the antibodies provided in Table 1.


Mass spectrometry (MS) is a primary technique for analysis of proteins on the basis of their mass-to-charge ratio (m/z). MS techniques generally include ionization of compounds and optional fragmentation of the resulting ions, as well as detection and analysis of the m/z of the ions and/or fragment ions followed by calculation of corresponding ionic masses. A “mass spectrometer” generally includes an ionizer and an ion detector. “Mass spectrometry,” “mass spec,” “mass spectroscopy,” and “MS” are used interchangeably throughout.


“Targeted mass spectrometry,” also referred to herein as “targeted mass spec,” “targeted MS,” and “tMS” increases the speed, sensitivity, and quantitative precision of mass spec analysis. Non-targeted mass spectrometry, sometimes referred to as “data-dependent scanning,” “discovery MS,” and “dMS” and targeted mass spec are alike in that in each, analytes (proteins, small molecules, or peptides) are infused or eluted from a reversed phase column attached to a liquid chromatography instrument and converted to gas phase ions by electrospray ionization. Analytes are fragmented in the mass spec (a process known as tandem MS or MS/MS), and fragment and parent masses are used to establish the identity of the analyte. Discovery MS analyzes the entire content of the MS/MS fragmentation spectrum. In contrast, in targeted mass spectrometry, a reference spectrum is used to guide analysis to only a few selected fragment ions rather than the entire content.


“Multiple reaction monitoring,” “MRM,” “selected reaction monitoring,” and “SRM” are used interchangeably throughout to refer to a type of targeted mass spectrometry that relies on a unique scanning mode accessible on triple-quadrupole (QQQ) instruments. See, e.g., Chambers et al., Expert Rev. Proteomics, 1-12 (2014).


“Parallel Reaction Monitoring,” and “PRM” are used interchangeably herein to describe another type of targeted mass spec wherein the second mass analyzer used in SRM (quadrupole) is substituted by a high resolution orbitrap mass analyzer in PRM. Unlike SRM, which allows the measuring of one single transition at a given point in time, PRM allows parallel monitoring in one MS/MS spectrum. PRM also allows for the separation of ions with close m/z values (i.e., within a 10 ppm range), and may therefore allow for lower limits of detection and quantification (LOD or LLOD and LOQ or LLOQ).


The methods disclosed herein may be applied to any type of MS analysis. The disclosure is not limited by the specific equipment or analysis used. The use of any equipment with the intent of analyzing the m/z of a sample would be included in the definition of mass spectrometry. Non-limiting examples of MS analysis and/or equipment that may be used include electrospray ionization, ion mobility, time-of-flight, tandem, ion trap, MRM, SRM, MRM/SRM, PRM, and Orbitrap. The disclosure is neither limited by the type of ionizer or detector used in the MS analysis nor by the specific configuration of the MS. The disclosure is not limited to use with specific equipment or software. The disclosure is not limited to the equipment and software described in the Examples.


In some embodiments, methods of immunoprecipitating an AKT-mTOR pathway protein are provided, comprising contacting a biological sample with at least one antibody recited in Table 1. The immunoprecipitating method may be single-plex or multi-plex. A “single-plex” IP utilizes one antibody per assay, whereas a “multi-plex” IP utilizes more than one antibody per assay.


In some embodiments, an IP-MS method for detecting and quantifying phosphorylated and non-phosphorylated AKT-mTOR pathway proteins is provided. The methods may comprise contacting a biological sample with at least one antibody recited in Table 1, digesting the immunoprecipitated protein(s), and assaying the digested proteins via mass spectrometry. The IP and MS may be single-plex or multi-plex. A “single-plex” MS refers to monitoring a single peptide in a single MS run, whereas a “mulit-plex” MS refers to monitoring more than one target peptides in a single MS run.


Table 1 provides a listing of antibodies useful in the IP and IP-MS methods described herein. Table 2 provides a listing of antibodies that are known to bind to their antigen AKT-mTOR protein, but were found to be less useful in the IP and IP-MS methods described herein. FIG. 11 and Table 3 provide a summary of antibodies useful in IP of AKT-mTOR pathway proteins, as validated by Western Blot.









TABLE 1







List of IP to MS validated antibodies for AKT-mTOR Pathway Proteins








Antibody Name
Company/Catalog Number





AKT1 Antibody
Millipore/07-416


AKT (pan) Antibody
Cell Signaling Technology/2920


AKT2 Antibody
Cell Signaling Technology/3063


phospho AKT2 (pSer474) Antibody
Thermo Fisher Scientific/PA5-35676


AKT1 Antibody
Cell Signaling Technology/2967


phospho AKT (pSer473) Antibody
Thermo Fisher Scientific/700392


phospho AKT (pSer473) Antibody
Cell Signaling Technology/4060


Anti-phospho-IGF-1R (Tyr1161/
Millipore/ABE332


Tyr1165/Tyr1166) Antibody



Phospho-IGF1 Rec pTyr1158 +
Thermo Fisher Scientific/PA1-26725


1162 + 1163 Antibody



Phospho-IGF1R pTyr1161 Antibody
Thermo Fisher Scientific/PA5-35769


Phospho-IGF-I Receptor β
Cell Signaling Technology/3021


(Tyr1131)/Insulin



Receptor β (Tyr1146) Antibody



IGF-I Receptor β Antibody
Cell Signaling Technology/9750


IGF-I Receptor β Antibody
Cell Signaling Technology/3027


Insulin Receptor β Antibody
Cell Signaling Technology/3020


INSR/Insulin Receptor Antibody
Thermo Fisher Scientific/



MA1-10865


Anti-α-Insulin Receptor Antibody,
Millipore/07-724


β subunit Antibody



INSR/Insulin Receptor
Thermo Fisher Scientific/


alpha Antibody
MA5-13759


Anti-Insulin Receptor
abcam/ab5678


(phospho Y972) Antibody



IRS-1 Antibody
Cell Signaling Technology/2382


IRS-1 Antibody
Cell Signaling Technology/3407


IRS-1 Antibody
Millipore/06-248


IRS-1 Antibody
Millipore/05-784R


IRS-1 Antibody
Millipore/05-1085


IRS1 (pSer312) polyclonal
Abnova/PAB12627


Antibody



Anti-phospho-IRS1 (Ser307 mouse/
Millipore/05-1087


Ser312 human) Antibody



Phospho-IRS-1 (pSer1101)
Cell Signaling Technology/2385


Antibody



mTOR Antibody
Cell Signaling Technology/2972


mTOR Antibody
Millipore/07-1415


mTOR Antibody
abcam/ab2732


mTOR Antibody
abcam/ab25880


mTOR Antibody
Thermo Fisher Scientific/PA1-518


Phospho-mTOR (pSer2448)
Thermo Fisher Scientific/PA5-35652


Antibody



Phospho-mTOR (pSer2448)
Cell Signaling Technology/5536


Antibody



Phospho-mTOR (pSer2448)
Abgent/AP50437


Antibody



S6K Antibody
Thermo Fisher Scientific/PA5-12726


S6K Antibody
Thermo Fisher Scientific/PA5-12723


S6K1 Antibody
Thermo Fisher Scientific/PA1-31167


Anti-S6K1 Antibody
abcam/ab9366


S6K Antibody
Thermo Fisher Scientific/PA5-27853


Phospho-p70 S6 Kinase (pThr389/
Thermo Fisher Scientific/PA5-35701


pThr412) Antibody



Phospho-p70 S6 Kinase (pThr389)
Thermo Fisher Scientific/701064


Antibody



Phospho-p70 S6 Kinase (pThr421/
Cell Signaling Technology/9204


pSer424) Antibody



Phospho-p70 S6 Kinase pThr389
Thermo Fisher Scientific/MA5-15202


Antibody



Phospho-GSK-3α/β (pSer21/pSer9)
Cell Signaling Technology/9327


Antibody



GSK3α Antibody
Cell Signaling Technology/4337


GSK3α Antibody
Cell Signaling Technology/4818


Phospho-GSK-3α (Ser21) Antibody
Cell Signaling Technology/8452


Phospho-GSK-3α (Ser21) Antibody
Cell Signaling Technology/9316


Phospho-GSK-3α/β (pSer21/pSer9)
Cell Signaling Technology/8566


Antibody



GSK3β Antibody
Thermo Fisher Scientific/MA5-15109


GSK3β Antibody
Thermo Fisher Scientific/PA5-29251


GSK3β Antibody
Thermo Fisher Scientific/PA5-29265


GSK3β Antibody
Cell Signaling Technology/12456


Phospho-GSK-3β (pSer9) Antibody
Cell Signaling Technology/5558


Phospho-Tuberin/TSC2 pSer939
Thermo Fisher Scientific/710395


Antibody



Phospho-TSC2 pSer939 Antibody
Thermo Fisher Scientific/PA5-12845


Phospho-TSC2 pSer939 Antibody
abcam/ab59269


Phospho-TSC2 pSer939 Antibody
abcam/ab52962


Anti-TSC2 Antibody
abcam/ab52936


Anti-TSC2 Antibody
Cell Signaling Technology/4308


Anti-TSC2 Antibody
Thermo Fisher Scientific/PA5-20132


Anti-TSC2 Antibody
Cell Signaling Technology/3990


Anti-TSC2 Antibody
Thermo Fisher Scientific/MA5-15004


S6 Ribosomal Protein Antibody
Thermo Fisher Scientific/701374


S6 Ribosomal Protein Antibody
Thermo Fisher Scientific/710405


S6 Ribosomal Protein Antibody
Thermo Fisher Scientific/PA5-11818


Phospho-S6 Ribosomal Protein
Thermo Fisher Scientific/701363


pSer235 + 236 Antibody



RPS6 Antibody
Thermo Fisher Scientific/PA5-26041


Anti-PRAS40 Antibody
abcam/ab72321


Anti-PRAS40 Antibody
Thermo Fisher Scientific/PA5-35143


Anti-PRAS40 Antibody
R&D System/MAB6408 (R&D)


Anti-PRAS40 Antibody
Cell Signaling Technology/2691


Phospho-PRAS40 (pThr246)
Cell Signaling Technology/2997


Antibody



Phospho-PRAS40 (pThr246)
Cell Signaling Technology/13175


Antibody



Phospho-PRAS40 (pThr246)
R&D System/MAB6890


Antibody



Phospho-PTEN (pSer380) Antibody
Cell Signaling Technology/9551


PTEN Antibody
Cell Signaling Technology/9188


AKT pan Antibody
Thermo Fisher Scientific/44-609G


mTOR Antibody
Thermo Fisher Scientific/PA1-188


IRS1 Antibody
Thermo Fisher Scientific/710009


IRS1 Antibody
Thermo Fisher Scientific/AH01322


IGFIR Antibody
Thermo Fisher Scientific/39-6700


TSC2 Antibody
Thermo Fisher Scientific/AHO1422


TSC2 Antibody
Thermo Fisher Scientific/730014


PTEN Antibody
Thermo Fisher Scientific/51-2400
















TABLE 2







List of IP to MS less successful


antibodies for AKT-mTOR Pathway Proteins








Antibody Name
Company/Catalog Number





Phospho-Akt (Ser473) Antibody
Cell Signaling Technology/4051


AKT1 Antibody
Thermo Fisher Scientific/PA5-23780


AKT2 Antibody
Thermo Fisher Scientific/MA1-034


Phospho-AKT1 pSer473 Antibody
Thermo Fisher Scientific/MA1-20325


Phospho-IGF-I Receptor β
Cell Signaling Technology/6113


(Tyr1316) Antibody



Phospho-IGF-I Receptor β
Cell Signaling Technology/3021


(Tyr1131)/Insulin



Receptor β (Tyr1146) Antibody



IGF-I Receptor β Antibody
Cell Signaling Technology/3018


IGF-IR/IGF1 Receptor alpha
Thermo Fisher Scientific/MA5-13817


Antibody



IGF-IR/IGF1 Receptor alpha
Thermo Fisher Scientific/MA5-13799


Antibody



Anti-IGF1 Receptor (phospho
Abcam/ab5680


Y1162 + Y1163) Antibody



IGF-IR/IGF1 Receptor alpha
Thermo Fisher Scientific/MA5-13802


Antibody



IGF-IR/IGF1 Receptor Antibody
Thermo Fisher Scientific/MA1-10853


Phospho-IGF-IR beta pTyr1135/
Thermo Fisher Scientific/MA5-15148


1136 + IR beta pTyr1150/1151



Antibody



Phospho-IGF-IR + IR pTyr1162 +
Thermo Fisher Scientific/700393


1163 Antibody



Phospho-IGF-IR pTyr1135 + 1163
Thermo Fisher Scientific/701067


Antibody



Phospho-IGF1 Rec. pTyr1162 +
Thermo Fisher Scientific/PA1-26724


1163 Antibody



Anti-phospho-IR/IGF1R (Tyr1158)
Millipore/07-839


Antibody



Insulin Receptor (β-Subunit)
Thermo Fisher Scientific/MS-635-P1


Anti-Insulin Receptor (pTyr1162/
Millipore/407707


1163) Antibody



Anti-phospho-IR/IGF1R
Millipore/07-841


(Tyr1158/Tyr1162/Tyr1163)



Antibody



Phospho-IRS-1 pSer312 Antibody
Thermo Fisher Scientific/PA5-35670


Phospho-IRS-1 (Ser307) Antibody
Cell Signaling Technology/2381


Phospho-IRS-1 (Ser1101) Antibody
Cell Signaling Technology/2385


Phospho-IRS-1 (Ser318) Antibody
Cell Signaling Technology/5610


p70 S6 Kinase Antibody
Cell Signaling Technology/9202


Phospho-p70 S6 Kinase (Thr389)
Thermo Fisher Scientific/MA5-15117


Antibody



Phospho-S6 Ribosomal Protein
Thermo Fisher Scientific/710394


pSer235 + 236 Antibody



Phospho-p70 S6 Kinase pThr389
Thermo Fisher Scientific/710095


Antibody



p70 S6 Kinase Antibody
Thermo Fisher Scientific/701261


Phospho-p70 S6 Kinase pThr389
Thermo Fisher Scientific/PA1-526


Antibody



GSK-3 alpha Antibody
Novus Biologicals/NB110-87048


GSK3 alpha Antibody
Thermo Fisher Scientific/PA5-15400


GSK3 alpha Antibody
Thermo Fisher Scientific/PA1-25969


GSK3 beta Antibody
Thermo Fisher Scientific/MA1-7621


GSK3B Antibody
Thermo Fisher Scientific/PA1-27893


GSK-3 beta Antibody
Novus Biologicals/NBP1-04292


GSK3B Antibody
Thermo Fisher Scientific/MA5-15597


Anti-Tuberin (phospho S1254)
Abcam/ab133454


Antibody



TSC2 (phospho S939) Antibody
Abnova/PAB16959


Phospho-Tuberin/TSC2 (Thr1462)
Cell Signaling Technology/3611


Antibody



S6 Ribosomal Protein Antibody
Thermo Fisher Scientific/MA5-15123


Phospho-RSK3 pThr356 + Ser360
Thermo Fisher Scientific/PA5-17554


Antibody



Non-Phospho PTEN (Ser380 +
Thermo Fisher Scientific/PA5-17153


Thr382 + Thr383) Antibody



PTEN Antibody
ProSci/3515


PTEN Antibody
ProSci/3517









The immunoprecipitated AKT-mTOR pathway proteins may be reduced and alkylated prior to fragmentation (e.g., digestion). Samples that have been reduced and alkylated may comprises modifications, such as to cysteine residues (e.g., CAM). Where an AKT-mTOR peptide of SEQ ID NO: 1-424 shows modification resulting from, for example, reduction/alkylation, the non-modified peptide is also encompassed. For example, in each instance where an AKT-mTOR pathway peptide of SEQ ID NO: 1-424 is referred to, also encompassed are unmodified peptides of SEQ ID NO: 1-424.


The samples may optionally be desalted prior to analysis by mass spectrometry. Both enzymatic and chemical digestion is encompassed. Enzymatic digestion includes, but is not limited to, digestion with a protease such as, for example, trypsin, chymotrypsin, AspN, GluC, LysC, LysN, ArgC, proteinase K, pepsin, Clostripain, Elastase, GluC biocarb, LysC/P, LysN Promise, Protein Endopeptidase, Staph Protease or thermolysin. Chemical digestion includes use of, for example, CNBr, iodosobenzoate and formic acid.


In some embodiments, after fragmentation (e.g., digestion), peptide samples are analyzed by mass spectrometry (MS), and the resulting spectra are compared with theoretical spectra from known proteins to determine the peptides and proteins in a sample. For AKT-mTOR pathway proteins, discovery MS is cumbersome and time consuming and is not a viable clinical method. Therefore, the inventors have identified novel peptides that associate with AKT-mTOR pathway proteins for use in the IP-MS methods of the disclosure. Use of these peptides in targeted MS, and IP-targeted MS methods allows quantitation of even low abundant AKT-mTOR proteins. Moreover, use of these peptides in targeted MS, and in IP-targeted MS methods, allows quantitation of phosphorylated AKT-mTOR proteins.


Theoretically, peptides useful in MS to detect and quantify AKT-mTOR pathway proteins can be designed by use of computer software and the like. However, many of these potential peptide sequences are unsuitable or ineffective for use in MS-based assays, including SRM/MRM and PRM. Because it was not possible to predict the most suitable peptides for MS analysis, it was necessary to experimentally identify modified and unmodified peptides to develop as clinical reagents. To complicate the analysis, it was discovered that certain peptides useful when assaying typical samples were not predictive when assaying samples that had undergone immunoprecipitation.


Typically, targeted MS is performed by quantifying specific unique peptides of the protein. In some embodiments, known amounts of isotope-labeled (e.g., heavy isotope-labeled) versions of these targeted peptides can be used as internal standards for absolute quantitation. In some instances, proteins of interest are not detectable even after identifying unique peptide standards. The combination of specific antibodies with specific target peptides has allowed the inventors to improve the sensitivity of detection of AKT-mTOR pathway proteins by MS, and has allowed for lower levels of detection and lower levels of quantification than ever previously seen. See, e.g., FIG. 4.


In some embodiments, the AKT-mTOR pathway peptides provided in the kits, and useful in the described methods, are listed in Table 3. SEQ ID Nos: 1-212 are native peptide sequences useful in identifying the AKT-mTOR pathway proteins recited in the “Target ID” column. Certain peptide sequences are phosphorylated at certain residues as shown in parentheses “(P03H2)” following the modified residue.


Certain peptides are modified at cysteine residues as shown by “(CAM)” following the modified residue. The “CAM” post-translational modification is well known to those of skill in the art to mean carbamidomethylation, resulting from alkylation of the protein/peptide. The peptides may be as shown in Table 3, or may be non-modified version of these peptides lacking carbamidomethylation.









TABLE 3







List of peptides to quantitate AKT-mTOR Pathway proteins













SEQ

SEQ


Target
Native Peptide
ID
Internal Standard
ID


ID
Sequence
NO:
Peptide Sequence
NO:





AKT1_1
NDGTFIGYK
  1
NDGTFIGY[K(13C6; 15N2)]
213





AKT1_2
SLLSGLLK
  2
SLLSGLL[K(13C6; 15N2)]
214





AKT1_3
EAPLNNFSVAQCQLMK
  3
EAPLNNFSVAQCQLM
215





[K(13C6; 15N2)]






AKT1_4
RPHFPQF[S(PO3H2)]
  4
RPHFPQF[S(PO3H2)]YSASGT
216



YSASGTA

[A(13C3; 15N)]






AKT1_5
RPHFPQFSYSASGTA
  5
RPHFPQFSYSASGTA
217





[A(13C3; 15N)]






AKT2_1
SDGSFIGYK
  6
SDGSFIGY[K(13C6; 15N2)]
218





AKT2_2
SLLAGLLK
  7
SLLAGLL[K(13C6; 15N2)]
219





AKT2_3
THFPQF[S(PO3H2)]
  8
THFPQF[SPO3H2)]YSASI
220



YSASIRE

[R(13C6; 15N4)]E






AKT2_4
THFPQFSYSASIRE
  9
THFPQFSYSASI
221





[R(13C6; 15N4)]E






AKT3_1
LVPPFKPQVTSETDTR
 10
LVPPFKPQVTSETDT
222





[R(13C6; 15N4)]






AKT3_2
SLLSGLLIK
 11
SLLSGLLI[K(13C6; 15N2)]
223





IR_1
[C(CAM)]SVAAYVSAR
 12
[C(CAM)]SVAAYVSA
224





[R(13C6; 15N4)]






IR_2
CSVAAYVSAR
 13
CSVAAYVSA[R(13C6; 15N4)]
225





IR_3
GLKPWTQYAIFVK
 14
GLKPWTQYAIFV
226





[K(13C6; 15N2)]






IR_4
IELQA[C(CAM)]NQDTPEER
 15
IELQA[C(CAM)]NQDTPEE
227





[R(13C6; 15N4)]






IR_5
TIDSVTSAQELR
 16
TIDSVTSAQEL[R(13C6; 15N4)]
228





IR_6
TNCPATVINGQFVER
 17
INCPATVINGQFVE
229





[R(13C6; 15N4)]






IR_7
TN[C(CAM)]PATVINGQFV
 18
TN[C(CAM)]PATVINGQFVE
230



ER

[R(13C6; 15N4)]






IR_8
TNGDQASCENELLK
 19
INGDQASCENELL
231





[K(13C6; 15N2)]






IR_9
INGDQAS[C(CAM)]ENELLK
 20
INGDQAS[C(CAM)]ENELL
232





[K(13C6; 15N2)]






IR_10
VCHLLEGEK
 21
VCHLLEGE[K(13C6; 15N2)]
233





IR_11
V[C(CAM)]HLLEGEK
 22
V[C(CAM)]HLLEGE
234





[K(13C6; 15N2)]






IR_12
TVNESASLR
 23
TVNESASL[R(13C6; 15N4)]
235





IR_13
DIIKGEAETR
 24
DIIKGEAET[R(13C6; 15N4)]
236





IR/
DIYETDYYR
 25
DIYETDYY[R(13C6; 15N4)]
237


IGF1R_1









IR/
DIYETDYYRK
 26
DIYETDYYR[K(13C6; 15N2)]
238


IGF1R_2









IR/
DI[Y(PO3H2)]EIDYYR
 27
DI[Y(PO3H2)]EIDYY
239


IGF1R_3


[R(13C6; 15N4)]






IR/
DIYETD[Y(PO3H2)]YR
 28
DIYETD[Y(PO3H2)]Y
240


IGF1R_4


[R(13C6; 15N4)]






IR/
DIYETDY[Y(PO3H2)]R
 29
DIYETDY[Y(PO3H2)]
241


IGF1R_5


[R(13C6; 15N4)]






IR/
DIYETD[Y(PO3H2)]
 30
DIYETD[Y(PO3H2)][Y(PO3H2)]
242


IGF1R_6
[Y(PO3H2)]R

[R(13C6; 15N4)]






IR/
DI[Y(PO3H2)]ETD
 31
DI[Y(PO3H2)]ETD[Y(PO3H2)]Y
243


IGF1R_7
[Y(PO3H2)]YR

[R(13C6; 15N4)]






IR/
DI[Y(PO3H2)]EIDY
 32
DI[Y(PO3H2)]EIDY[Y(PO3H2)]
244


IGF1R_8
[Y(PO3H2)]R

[R(13C6; 15N4)]






IR/
DI[Y(PO3H2)]ETD
 33
DI[Y(PO3H2)]ETD[Y(PO3H2)]
245


IGF1R_9
[Y(PO3H2)][Y(PO3H2)]R

[Y(PO3H2)][R(13C6; 15N4)]






IGF1R_1
AENGPGPGVLVLR
 34
AENGPGPGVLVL
246





[R(13C6; 15N4)]






IGF1R_2
HYYYAGV[C(CAM)]VPA
 35
HYYYAGV[C(CAM)]VPA[C(CAM)]
247



[C(CAM)]PPNTYR

PPNTY[R(13C6; 15N4)]






IGF1R_3
HYYYAGVCVPACPPNTYR
 36
HYYYAGVCVPACPPNTY
248





[R(13C6; 15N4)]






IGF1R_4
LG[C(CAM)]SASNFVFAR
 37
LG[C(CAM)]SASNFVFA
249





[R(13C6; 15N4)]






IGF1R_5
LGCSASNFVFAR
 38
LGCSASNFVFA[R(13C6; 15N4)]
250





IGF1R_6
SLRPEMENNPVLAPPSLSK
 39
SLRPEMENNPVLAPPSLS
251





[K(13C6; 15N2)]






IGF1R_7
TTINNEYNYR
 40
TTINNEYNY[R(13C6; 15N4)]
252





IGF1R_8
VAGLESLGDLFPNLTVIR
 41
VAGLESLGDLFPNLTVI
253





[R(13C6; 15N4)]






IGF1R_9
YADGTIDIEEVTENPK
 42
YADGTIDIEEVIENP
254





[K(13C6; 15N2)]






IGF1R_10
YGSQVEDQRE[C(CAM)]
 43
YGSQVEDQRE[C(CAM)]VS
255



VSR

[R(13C6; 15N4)]






IGF1R_11
YGSQVEDQRECVSR
 44
YGSQVEDQRECVS
256





[R(13C6; 15N4)]






IGF1R_12
IDIHSCNHEAEK
 45
IDIHSCNHEAE[K(13C6; 15N2)]
257





IGF1R_13
GVVKDEPETR
 46
GVVKDEPET[R(13C6; 15N4)]
258





IRS1_1
ASSDGEGTMSRPASVDGSPV
 47
ASSDGEGTMSRPASVDGSPVSPSTN
259



SPSTNR

[R(13C6; 15N4)]






IRS1_2
[C(CAM)]GHSENFFFIEVGR
 48
[C(CAM)]GHSENFFFIEVG
260





[R(13C6; 15N4)]






IRS1_3
CGHSENFFFIEVGR
 49
CGHSENFFFIEVG
261





[R(13C6; 15N4)]






IRS1_4
[C(CAM)]TPGTGLGTSPAL
 50
[C(CAM)]TPGTGLGTSPALAGDEAA 
262



AGDEAASAADLDNR

SAADLDN[R(13C6; 15N4)]






IRS1_5
CTPGTGLGTSPALAGDEAAS
 51
CTPGTGLGTSPALAGDEAASAADLDN
263



AADLDNR

[R(13C6; 15N4)]






IRS1_6
HHLNNPPPSQVGLTR
 52
HHLNNPPPSQVGLT
264





[R(13C6; 15N4)]






IRS1_7
HSSETFSSTPSATR
 53
HSSETFSSTPSAT
265





[R(13C6; 15N4)]






IRS1_8
KGSGDYMPMSPK
 54
KGSGDYMPMSP[K(13C6; 15N2)]
266





IRS1_9
L[C(CAM)]GAAGGLENGLN
 55
L[C(CAM)]GAAGGLENGLNYIDLDLV
267



YIDLDLVK

[K(13C6; 15N2)]






IRS1_10
LCGAAGGLENGLNYIDLDLVK
 56
LCGAAGGLENGLNYIDLDLV
268





[K(13C6; 15N2)]






IRS1_11
SVSAPQQIINPIR
 57
SVSAPQQIINPI
269





[R(13C6; 15N4)]






IRS1_12
TESITATSPASMVGGKPGSFR
 58
TESITATSPASMVGGKPGSF
270





[R(13C6; 15N4)]






IRS1_13
TGIAAEEVSLPR
 59
TGIAAEEVSLP[R(13C6; 15N4)]
271





IRS1_14
SYPEEGLEMHPLER
 60
SYPEEGLEMHPLE
272





[R(13C6; 15N4)]






IRS1_15
THSAGTSPTITHQK
 61
THSAGTSPTITHQ
273





[K(13C6; 15N2)]






IRS1_16
AS[S(PO3H2)]DGEGTMSR
 62
AS[S(PO3H2)]DGEGTMSRPASVDG 
274



PASVDGSPVSPSTNR

SPVSPSTN[R(13C6; 15N4)]






IRS1_17
HS[S(PO3H2)]ETFSSTPS
 63
HS[S(PO3H2)]ETFSSTPSAT
275



ATR

[R(13C6; 15N4)]






IRS1_18
KGSGDYMPM[S(PO3H2)]PK
 64
KGSGDYMPM[S(PO3H2)]P
276





[K(13C6; 15N2)]






IRS1_19
KGSGDY[M(O)]P[M(O)]
 65
KGSGDY[M(O)]P[M(O)][S(PO3H2)]
277



[S(PO3H2)]PK

P[K(13C6; 15N2)]






IRS1_20
L[C(CAM)]GAAGGLENGLN
 66
L[C(CAM)]GAAGGLENGLN[Y(PO3H2)]
278



[Y(PO3H2)]IDLDLVK

IDLDLV[K(13C6; 15N2)]






IRS1_21
LCGAAGGLENGLN
 67
LCGAAGGLENGLN[Y(PO3H2)]IDL 
279



[Y(PO3H2)]IDLDLVK

DLV[K(13C6; 15N2)]






IRS1_22
TESITAT[S(PO3H2)]PAS
 68
TESITAT[S(PO3H2)]PASMVGGKP 
280



MVGGKPGSFR

GSF[R(13C6; 15N4)]






IRS1_23
TESITAT[S(PO3H2)]PAS
 69
TESITAT[S(PO3H2)]PAS[M(O)]
281



[M(O)]VGGKPGSFR

VGGKPGSF[R(13C6; 15N4)]






TSC2_1
APAQTPAEPTPGYEVGQR
 70
APAQTPAEPTPGYEVGQ
282





[R(13C6; 15N4)]






TSC2_2
DSFRARSTSLNERPK
 71
DSFRARSTSLNERP
283





[K(13C6; 15N2)]






TSC2_3
EAPAKLESQAGQQVSR
 72
EAPAKLESQAGQQVS
284





[R(13C6; 15N4)]






TSC2_4
GYTISDSAPSR
 73
GYTISDSAPS[R(13C6; 15N4)]
285





TSC2_5
LISSVEDFTEFV
 74
LISSVEDFTEF[V(13C5; 15N)]
286





TSC2_6
LVTVTTSVGTGTR
 75
LVTVTTSVGTGT
287





[R(13C6; 15N4)]






TSC2_7
SQSGTLDGESAAWSASGEDSR
 76
SQSGTLDGESAAWSASGEDS
288





[R(13C6; 15N4)]






TSC2_8
SVQLLDQIPSYDTHK
 77
SVQLLDQIPSYDTH
289





[K(13C6; 15N2)]






TSC2_9
VGALDVPASQFLGSATSPGPR
 78
VGALDVPASQFLGSATSPGP
290





[R(13C6; 15N4)]






TSC2_10
VVSSEGGRPSVDLSFQPSQP
 79
VVSSEGGRPSVDLSFQPSQPLS
291



LSK

[K(13C6; 15N2)]






TSC2_11
YTEFLTGLGR
 80
YTEFLTGLG[R(13C6; 15N4)]
292





2SC2_12
YVFSNFTAVPK
 81
YVFSNFTAVP[K(13C6; 15N2)]
293





TSC2_13
SNPTDIYPSK
 82
SNPTDIYPS[K(13C6; 15N2)]
294





TSC2_14
FNSCYLDEYIAR
 83
FNSCYLDEYIA[R(13C6; 15N4)]
295





TSC2_15
GQPEGPLPSSSPR
 84
GQPEGPLPSSSP
296





[R(13C6; 15N4)]






TSC2_16
SLLGLDSGELQSGPESSSSP
 85
SLLGLDSGELQSGPESSSSPGVHV
297



GVHVR

[R(13C6; 15N4)]






TSC2_17
DSFRARST[S(PO3H2)]LN
 86
DSFRARST[S(PO3H2)]LNERP
298



ERPK

[K(13C6; 15N2)]






TSC2_18
GY[T(PO3H2)]ISDSAPSR
 87
GY[T(PO3H2)]ISDSAPS
299





[R(13C6; 15N4)]






TSC2_19
LI[S(PO3H2)]SVEDFTEFV
 88
LI[S(PO3H2)]SVEDFTEF
300





[V(13C5; 15N)]






TSC2_20
LIS[S(PO3H2)]VEDFTEFV
 89
LIS[S(PO3H2)]VEDFTEF
301





[V(13C5; 15N)]






TSC2_21
LI[S(PO3H2)][S(PO3H2)]
 90
LI[S(PO3H2)][S(PO3H2)]VEDF 
302



VEDFTEFV

TEF[V(13C5; 15N)]






TSC2_22
ST[S(PO3H2)]LNERPK
 91
ST[S(PO3H2)]LNERP
303





[K(13C6; 15N2)]






TSC2_23
STSLNERPK
 92
STSLNERP[K(13C6; 15N2)]
304





mTOR_1
AVLALHQDLFSLAQQ
 93
AVLALHQDLFSLAQQ[C(CAM)]ID
305



[C(CAM)]IDK

[K(13C6; 15N2)]






mTOR_2
AVLALHQDLFSLAQQCIDK
 94
AVLALHQDLFSLAQQCID
306





[K(13C6; 15N2)]






mTOR_3
DLELAVPGTYDPNQPIIR
 95
DLELAVPGTYDPNQPII
307





[R(13C6; 15N4)]






mTOR_4
GNNLQDTLR
 96
GNNLQDTL[R(13C6; 15N4)]
308





mTOR_5
GPTPAILESLISINNK
 97
GPTPAILESLISINN
309





[K(13C6; 15N2)]






mTOR_6
GYTLADEEEDPLIYQHR
 98
GYTLADEEEDPLIYQH
310





[R(13C6; 15N4)]






mTOR_7
IHGALLILNELVR
 99
IHGALLILNELV
311





[R(13C6; 15N4)]






mTOR_8
IQSIAPSLQVITSK
100
IQSIAPSLQVITS
312





[K(13C6; 15N2)]






mTOR_9
LFDAPEAPLPSR
101
LFDAPEAPLPS[R(13C6; 15N4)]
313





mTOR_10
LGEWQLNLQGINESTIPK
102
LGEWQLNLQGINESTIP
314





[K(13C6; 15N2)]






mTOR_11
LIHQLLTDIGR
103
LIHQLLTDIG[R(13C6; 15N4)]
315





mTOR_12
SPSSEVWFDR
104
SPSSEVWFD[R(13C6; 15N4)]
316





mTOR_13
TDSYSAGQSVEILDGVELGE
105
TDSYSAGQSVEILDGVELGEPAH
317



PAHK

[K(13C6; 15N2)]






mTOR_14
TLVLLLGVDPSR
106
TLVLLLGVDPS[R(13C6; 15N4)]
318





mTOR_15
VEVFEHAVNNTAGDDLAK
107
VEVFEHAVNNTAGDDLA
319





[K(13C6; 15N2)]






mTOR_16
VLGLLGALDPYK
108
VLGLLGALDPY[K(13C6; 15N2)]
320





mTOR_17
WTLVNDETQAK
109
WTLVNDETQA[K(13C6; 15N2)]
321





mTOR_18
ETSFNQAYGR
110
ETSFNQAYG[R(13C6; 15N4)]
322





mTOR_19
TLDQSPELR
111
TLDQSPEL[R(13C6; 15N4)]
323





mTOR_20
TD[S(PO3H2)]YSAGQSVE
112
TD[S(PO3H2)]YSAGQSVEILDGVE
324



ILDGVELGEPAHK

LGEPAH[K(13C6; 15N2)]






mTOR_21
[T(PO3H2)]DSYSAGQSVE
113
[T(PO3H2)]DSYSAGQSVEILDGVE
325



ILDGVELGEPAHK

LGEPAH[K(13C6; 15N2)]






mTOR_22
[T(PO3H2)]D[S(PO3H2)]
114
[T(PO3H2)]D[S(PO3H2)]YSAGQSV
326



YSAGQSVEILDGVELGEPAHK

EILDGVELGEPAH[K(13C6; 15N2)]






GSK3a_1
DIKPQNLLVDPDTAVLK
115
DIKPQNLLVDPDTAVL
327





[K(13C6; 15N2)]






GSK3a_2
LSPLEA[C(CAM)]AHSFFD
116
LSPLEA[C(CAM)]AHSFFDEL
328



ELR

[R(13C6; 15N4)]






GSK3a_3
LSPLEACAHSFFDELR
117
LSPLEACAHSFFDEL
329





[R(13C6; 15N4)]






GSK3a_4
SLAYIHSQGV[C(CAM)]HR
118
SLAYIHSQGV[C(CAM)]H
330





[R(13C6; 15N4)]






GSK3a_5
SLAYIHSQGVCHR
119
SLAYIHSQGVCH
331





[R(13C6; 15N4)]






GSK3a_6
SQEVAYTDIK
120
SQEVAYTDI[K(13C6; 15N2)]
332





GSK3a_7
TPPEAIAL[C(CAM)]SSLL
121
TPPEAIAL[C(CAM)]SSLLEYTPSS
333



EYTPSSR

[R(13C6; 15N4)]






GSK3a_8
TPPEAIALCSSLLEYTPSSR
122
TPPEAIALCSSLLEYTPSS
334





[R(13C6; 15N4)






GSK3a_9
TSSFAEPGGGGGGGGGGPGG
123
TSSFAEPGGGGGGGGGGPGGSASGPG
335



SASGPGGTGGGK

GTGGG[K(13C6; 15N2)]






GSK3a_10
VTTVVATLGQGPER
124
VTTVVATLGQGPE
336





[R(13C6; 15N4)]






GSK3a_11
DSGKVTTVVATLGQGPER
125
DSGKVTTVVATLGQGPE
337





[R(13C6; 15N4)]






GSK3a_12
YFFYSSGEK
126
YFFYSSGE[K(13C6; 15N2)]
338





GSK3a_13
TS[S(PO3H2)]FAEPGGGG
127
TS[S(PO3H2)]FAEPGGGGGGGGGG 
339



GGGGGGPGGSASGPGGTGGGK

PGGSASGPGGTGGG






[K(13C6; 15N2)]






GSK3b_1
DEVYLNLVLDYVPETVYR
128
DEVYLNLVLDYVPETVY
340





[R(13C6; 15N4)]






GSK3b_2
DIKPQNLLLDPDTAVLK
129
DIKPQNLLLDPDTAVL
341





[K(13C6; 15N2)]






GSK3b_3
DTPALFNFTTQELSSNPPLA
130
DTPALFNFTTQELSSNPPLATILIPP
342



TILIPPHAR

HA[R(13C6; 15N4)]






GSK3b_4
L[C(CAM)]DSGELVAIK
131
L[C(CAM)]DSGELVAI
343





[K(13C6; 15N2)]






GSK3b_5
LCDSGELVAIK
132
LCDSGELVAI[K(13C6; 15N2)]
344





GSK3b_6
LLEYTPTAR
133
LLEYTPTA[R(13C6; 15N4)]
345





GSK3b_7
SLAYIHSFGI[C(CAM)]HR
134
SLAYIHSFGI[C(CAM)]H 
346





[R(13C6; 15N4)]






GSK3b_8
SLAYIHSFGICHR
135
SLAYIHSFGICH
347





[R(13C6; 15N4)]






GSK3b_9
TTSFAES[C(CAM)]KPVQQ
136
TTSFAES[C(CAM)]KPVQQPSAFGS 
348



PSAFGSMK

M[K(13C6; 15N2)]






GSK3b_10
TTSFAESCKPVQQPSAFGSMK
137
TTSFAESCKPVQQPSAFGSM
349





[K(13C6; 15N2)]






GSK3b_11
TTSFAES[C(CAM)]KPVQQ
138
TTSFAES[C(CAM)]KPVQQPSAFGS 
350



PSAFGS[M(O)]K

[M(O)][K(13C6; 15N2)]






GSK3b_12
TTSFAESCKPVQQPSAFGS
139
TTSFAESCKPVQQPSAFGS[M(O)]
351



[M(O)]K

[K(13C6; 15N2)]






GSK3b_13
VTTVVATPGQGPDRPQEVSY
140
VTTVVATPGQGPDRPQEVSYTDTK
352



TDTK








GSK3b_14
KLDHCNIVR
141
KLDHCNIV[R(13C6; 15N4)]
353





GSK3b_15
DSSGTGHFTSGVR
142
DSSGTGHFTSGV[R(13C6; 15N4)]
354





GSK3b_16
TT[S(PO3H2)]FAES[C(CAM)]
143
TT[S(PO3H2)]FAES[C(CAM)]KP
355



KPVQQPSAFGS[M(O)]K

VQQPSAFGS[M(O)][K(13C6; 15N2)]






GSK3b_17
TT[S(PO3H2)]FAESCKPV
144
TT[S(PO3H2)]FAESCKPVQQPSAF 
356



QQPSAFGS[M(O)]K

GS[M(O)][K(13C6; 15N2)]






GSK3b_18
TT[S(PO3H2)]FAES
145
TT[S(PO3H2)]FAES[C(CAM)]KP
357



[C(CAM)]KPVQQPSAFGSMK

VQQPSAFGSM[K(13C6; 15N2)]






GSK3b_19
TT[S(PO3H2)]FAESCKPV
146
TT[S(PO3H2)]FAESCKPVQQPSAF
358



QQPSAFGSMK

GSM[K(13C6; 15N2)]






GSK3a/
GEPNVSYI[C(CAM)]SR
147
GEPNVSYI[C(CAM)]S
359


GSK3b_1


[R(13C6; 15N4)]






GSK3a/
GEPNVSYICSR
148
GEPNVSYICS[R(13C6; 15N4)]
360


GSK3b_2









GSK3a/
GEPNVS[Y(PO3H2)]I
149
GEPNVS[Y(PO3H2)]I[C(CAM)]S
361


GSK3b_3
[C(CAM)]SR

[R(13C6; 15N4)]






GSK3a/
GEPNVS[Y(PO3H2)]ICSR
150
GEPNVS[Y(PO3H2)]ICS
362


GSK3b_4


[R(13C6; 15N4)]






GSK3a/
GEPNV[S(PO3H2)]YI
151
GEPNV[S(PO3H2)]YI[C(CAM)]S
363


GSK3b_5
[C(CAM)]SR

[R(13C6; 15N4)]






GSK3a/
GEPNV[S(PO3H2)]YICSR
152
GEPNV[S(PO3H2)]YICS
364


GSK3b_6


[R(13C6; 15N4)]






GSK3a/
GEPNV[S(PO3H2)][Y(PO3H2)]
153
GEPNV[S(PO3H2)][Y(PO3H2)]I 
365


GSK3b_7
I[C(CAM)]SR

[C(CAM)]S[R(13C6; 15N4)]






GSK3a/
GEPNV[S(PO3H2)][Y(PO3H2)]
154
GEPNV[S(PO3H2)][Y(PO3H2)]I 
366


GSK3b_8
ICSR

CS[R(13C6; 15N4)]






GSK3a/
TPPEAIALCSR
155
TPPEAIALCS[R(13C6; 15N4)]
367


GSK3b_9









GSK3a/
TPPEAIAL[C(CAM)]SR
156
TPPEAIAL[C(CAM)]S
368


GSK3b_10


[R(13C6; 15N4)]






p70S6K_1
DGFYPAPDFR
157
DGFYPAPDF[R(13C6; 15N4)]
369





p70S6K_2
DLKPENIMLNHQGHVK
158
DLKPENIMLNHQGHV
370





[K(13C6; 15N2)]






p70S6K_3
FEISETSVNR
159
FEISETSVN[R(13C6; 15N4)]
371





p70S6K_4
FSPGDFWGR
160
FSPGDFWG[R(13C6; 15N4)]
372





p70S6K_5
HINWEELLAR
161
HINWEELLA[R(13C6; 15N4)]
373





p70S6K_6
HPFIVDLIYAFQTGGK
162
HPFIVDLIYAFQTGG
374





[K(13C6; 15N2)]






p70S6K_7
IRPE[C(CAM)]FELLR
163
IRPE[C(CAM)]FELL
375





[R(13C6; 15N4)]






p70S6K_8
IRPECFELLR
164
IRPECFELL[R(13C6; 15N4)]
376





p70S6K_9
LGAGPGDAGEVQAHPFFR
165
LGAGPGDAGEVQAHPFF
377





[R(13C6; 15N4)]






p70S6K_10
LNLPPYLTQEAR
166
LNLPPYLTQEA[R(13C6; 15N4)]
378





p70S6K_11
LTDFGL[C(CAM)]K
167
LTDFGL[C(CAM)]
379





[K(13C6; 15N2)]






p70S6K_12
LTDFGLCK
168
LTDFGLC[K(13C6; 15N2)]
380





p70S6K_13
QTPVDSPDDSTLSESANQVF
169
QTPVDSPDDSTLSESANQVFLGFTYV
381



LGFTYVAPSVLESVK

APSVLESV[K(13C6; 15N2)]






p70S6K_14
TPVSPVK
170
TPVSPV[K(13C6; 15N2)]
382





p70S6K_15
TPVSPVKFSPGDFWGR
171
TPVSPVKFSPGDFWG
383





[R(13C6; 15N4)]






p70S6K_16
QTPVDSPDDSTLSESANQVF
172
QTPVDSPDDSTLSESANQVFLGF
384



LGF[T(PO3H2)]YVAPSVL

[T(PO3H2)]YVAPSVLESV




ESVK

[K(13C6; 15N2)]






p70S6K_17
QTPVD[S(PO3H2)]PDDST
173
QTPVD[S(PO3H2)]PDDSTLSESAN
385



LSESANQVFLGFTYVAPSVL

QVFLGFTYVAPSVLESV




ESVK

[K(13C6; 15N2)]






p70S6K_18
QTPVD[S(PO3H2)]PDDST
174
QTPVD[S(PO3H2)]PDDSTLSESAN 
386



LSESANQVFLGF[T(PO3H2)]

QVFLGF[T(PO3H2)]YVAPSVLESV




YVAPSVLESVK

[K(13C6; 15N2)]






p70S6K_19
[T(PO3H2)]PVSPVK
175
[T(PO3H2)]PVSPV[K(13C6; 15N2)]
387





p70S6K_20
TPV[S(PO3H2)]PVK
176
TPV[S(PO3H2)]PV[K(13C6; 15N2)]
388





p70S6K_21
[T(PO3H2)]PV[S(PO3H2)]
177
[T(PO3H2)]PV[S(PO3H2)]PV
389



PVK

[K(13C6; 15N2)]






p70S6K_22
TPV[S(PO3H2)]PVKFSPG
178
TPV[S(PO3H2)]PVKFSPGDFWG
390



DFWGR

[R(13C6; 15N4)]






p70S6K_23
[T(PO3H2)]PV[S(PO3H2)]
179
[T(PO3H2)]PV[S(PO3H2)]PVKF
391



PVKFSPGDFWGR

SPGDFWG[R(13C6; 15N4)]






p70S6K_24
[T(PO3H2)]PVSPVKFSPG
180
[T(PO3H2)]PVSPVKFSPGDFWG
392



DFWGR

[R(13C6; 15N4)]






RPS6_1
DIPGLTDTTVPR
181
DIPGLTDTTVP[R(13C6; 15N4)]
393





RPS6_2
GHS[C(CAM)]YRPR
182
GHS[C(CAM)]YRP[R(13C6; 15N4)]
394





RPS6_3
GHSCYRPR
183
GHSCYRP[R(13C6; 15N4)]
395





RPS6_4
LNISFPATG[C(CAM)]QK
184
LNISFPATG[C(CAM)]Q
396





[K(13C6; 15N2)]






RPS6_5
LNISFPATGCQK
185
LNISFPATGCQ[K(13C6; 15N2)]
397





RPS6_6
MATEVAADALGEEWK
186
MATEVAADALGEEW[K(13C6; 15N2)]
398





RPS6_7
RRRLSSLRASTSK
187
RRRLSSLRASTS[K(13C6; 15N2)]
399





RPS6_8
RRRL[S(PO3H2)]SLRAST
188
RRRL[S(PO3H2)]SLRASTS
400



SK

[K(13C6; 15N2)]






RPS6_9
RRRLS[S(PO3H2)]LRAST
189
RRRLS[S(PO3H2)]LRASTS
401



SK

[K(13C6; 15N2)]






RPS6_10
RRRL[S(PO3H2)][S(PO3H2)]
190
RRRL[S(PO3H2)][S(PO3H2)]LR
402



LRASTSK

ASTS[K(13C6; 15N2)]






PRAS40_1
AATAARPPAPPPAPQPPSPT
191
AATAARPPAPPPAPQPPSPTPSPPRP
403



PSPPRPTLAR

TLA[R(13C6; 15N4)]






PRAS40_2
[C(CAM)]LHDIALAHR
192
[C(CAM)]LHDIALAH
404





[R(13C6; 15N4)]






PRAS40_3
CLHDIALAHR
193
CLHDIALAH[R(13C6; 15N4)]
405





PRAS40_4
EAEDTQVFGDLPRPR
194
EAEDTQVFGDLPRP
406





[R(13C6; 15N4)]






PRAS40_5
SLPVSVPVWGFK
195
SLPVSVPVWGF[K(13C6; 15N2)]
407





PRAS40_6
SSDEENGPPSSPDLDR
196
SSDEENGPPSSPDLD
408





[R(13C6; 15N4)]






PRAS40_7
TEARSSDEENGPPSSPDLDR
197
TEARSSDEENGPPSSPDLD
409





R(13C6; 15N4)]






PRAS40_8
TGTELVLLTAAPPPPPRPGP
198
TGTELVLLTAAPPPPPRPGP[C(CAM)]
410



[C(CAM)]AYAAHGR

AYAAHG[R(13C6; 15N4)]






PRAS40_9
TGTELVLLTAAPPPPPRPGP
199
TGTELVLLTAAPPPPPRPGPCAYAAH
411



CAYAAHGR

G[R(13C6; 15N4)]






PRAS40_10
LNTSDFQK
200
LNTSDFQ[K(13C6; 15N2)]
412





PRAS40_11
EAEDTQVFGDLPRPRLNTSD
201
EAEDTQVFGDLPRPRLNTSDFQ 
413



FQK

[K(13C6; 15N2)]






PRAS40_12
GALAEAAR
202
GALAEAA[R(13C6; 15N4)]
414





PRAS40_13
ASGRPEELWEAVVGAAER
203
ASGRPEELWEAVVGAAE
415





[R(13C6; 15N4)]






PRAS40_14
LN[T(PO3H2)]SDFQK
204
LN[T(PO3H2)]SDFQ
416





[K(13C6; 15N2)]






PRAS40_15
EAEDTQVFGDLPRPRLN
205
EAEDTQVFGDLPRPRLN[T(PO3H2)]
417



[T(PO3H2)]SDFQK

SDFQ[K(13C6; 15N2)]






PTEN_1
YSDTTDSDPENEPFDEDQHT
206
YSDTTDSDPENEPFDEDQHTQIT
418



QITK

[K(13C6; 15N2)]






PTEN_2
YSDTTDSDPENEPFDEDQHT
207
YSDTTDSDPENEPFDEDQHTQIT
419



QITKV

[K(13C6; 15N2)]V






PTEN_3
NNIDDVVR
208
NNIDDVV[R(13C6; 15N4)]
420





PTEN_4
AQEALDFYGEVR
209
AQEALDFYGEV[R(13C6; 15N4)]
421





PTEN_5
IYSSNSGPTR
210
IYSSNSGPT[R(13C6; 15N4)]
422





PTEN_6
Y[S(PO3H2)]DTTDSDPEN
211
Y[S(PO3H2)]DTTDSDPENEPFDED
423



EPFDEDQHTQITK

QHTQIT[K(13C6; 15N2)]






PTEN_7
Y[S(PO3H2)]DTTDSDPEN
212
Y[S(PO3H2)]DTTDSDPENEPFDED
424



EPFDEDQHTQITKV

QHTQIT[K(13C6; 15N2)]V









In some embodiments, the peptides reagents are recited in Table 5 (SEQ ID Nos: 98, 96, 157, 163, 40, 42, 37, 25, 73, 80, 52, 57, 59, 208, 209, 16, 23, 124, 120, 195, 200, 129, 133, 1, 6, 27, 91, and 204). In some embodiments, the peptides of Table 5 are useful in multi-plex MS methods.


In some embodiments, protein samples are denatured or solubilized before fragmentation.


In some embodiments, the fragmentation protocol uses chemical cleavage. In some embodiments, the chemical cleavage uses CNBr. In some embodiments, the fragmentation protocol is done using an enzyme. In some embodiments, the fragmentation protocol uses MS-grade commercially available proteases. Examples of proteases that may be used to digest samples include trypsin, endoproteinase GluC, endoproteinase ArgC, pepsin, chymotrypsin, LysN protease, LysC protease, GluC protease, AspN protease, proteinase K, and thermolysin. In some embodiments, a mixture of different proteases are used and the individual results are combined together after the digestion and analysis. In some embodiments, the digestion is incomplete in order to see larger, overlapping peptides. In some embodiments, the antibody digestion is performed with IdeS, IdeZ, pepsin, or papain to generate large antibody domains for “middle-down” protein characterization. In some embodiments, the fragmentation protocol uses trypsin that is modified. In some embodiments, a protein:protease ratio (w/w) of 10:1, 20:1, 25:1, 50:1, 66:1, or 100:1 may be used. In some embodiments, the trypsin used is at a concentration of about 100 ng/ml-1 mg/ml, or about 100 ng/ml-500 μg/ml, or about 100 ng/ml-100 μg/ml, or about 1 μg/ml-1 mg/ml, or about 1 μg/ml-500 μg/ml, or about 1 μg/ml-100 μg/ml, or about 10 μg/mg-1 mg/ml, or about 10 μg/mg-500 μg/ml, or about 10 μg/mg-100 μg/ml. In some embodiments, the digestion step is for 10 minutes to 48 hours, or 30 minutes to 48 hours, or 30 minutes to 24 hours, or 30 minutes to 16 hours, or 1 hour to 48 hours, or 1 hour to 24 hours, or 1 hour to 16 hours, or 1 to 8 hours, or 1 to 6 hours, or 1 to 4 hours. In some embodiments, the digestion step is incubated at a temperature between 20° C. and 45° C., or between 20° C. and 40° C., or between 22° C. and 40° C., or between 25° C. and 37° C. In some embodiments, the digestion step is incubated at 37° C. or 30° C. In some embodiments, a step is included to end the digestion step. The step to end the digestion protocol may be addition of a stop solution or a step of spinning or pelleting of a sample. In some embodiments, the digestion is followed by guanidation.


In some embodiments, the fragmentation protocol includes use of protein gels. In some embodiments, the fragmentation protocol comprises in-gel digestion. An exemplary commercially available kit for performing in-gel digestion is the In-Gel Tryptic Digestion Kit (Thermo Fisher Cat#89871).


In some embodiments, the fragmentation protocol is carried out in solution. An exemplary commercially available kit for performing in-solution digestion is the In-Solution Tryptic Digestion and Guanidiation Kit (Thermo Fisher Cat#89895).


In some embodiments, the fragmentation protocol uses beads. In some embodiments, the fragmentation protocol comprises on-bead digestion. In some embodiments, agarose beads or Protein G beads are used. In some embodiments, magnetic beads are used.


In some embodiments, protein samples are separated using liquid chromatography before MS analysis. In some embodiments, fragmented samples are separated using liquid chromatography before MS analysis.


The IP and IP-MS methods described herein are capable of detecting phosphorylated AKT-mTOR pathway proteins, including those described in Table 4.









TABLE 4







List of Total and Phosphorylated


AKT-mTOR Pathway Target Proteins











Target
Target Name
Phosphorylation



ID No.
(Total)
Site







 1
AKT1
pSer473



 2
PTEN
pSer380



 3
IRS1
pSer312



 4
IR
pTyr1162/1163



 5
IGF-1R
pTyr1135/1136



 6
GSK3a
pSer21



 7
GSK3b
pSer9



 8
RPS6
pSer235/236



 9
PRAS40
pThr246



10
mTOR
pSer2448



11
p70S6K (S6K1)
pThr389



12
TSC2
pSer939










In some embodiments, the AKT-mTOR pathway peptides used in the MS methods described herein have limits of detection considered useful in clinical and research methods. See, e.g, Table 5. In some embodiments, the AKT-mTOR pathway peptides used in the MS and IP-MS methods comprise or consist of the peptides described in Table 5. In some embodiments, the peptides of Table 5 are detectably labelled. The peptides of SEQ ID NO: 163 may lack the “CAM” modification shown on the fifth amino acid.









TABLE 5







Lower Limit of Quantitation of


Peptides for AKT-mTOR Pathway Proteins













Lower limit of



Native
SEQ
Quantitation


Target ID
Peptide Sequence
ID NO:
(fmol)













mTOR_6
GYTLADEEEDPLIYQHR
98
0.69





mTOR_4
GNNLQDTLR
96
0.08





p70S6K_1
DGFYPAPDFR
157
0.23





p70S6K_7
IRPE[C(CAM)]FELLR
163
6.17





IGF1R_7
TTINNEYNYR
40
0.08





IGF1R_9
YADGTIDIEEVTENPK
42
0.69





IGF1R_4
LG[C(CAM)]SASNFVF
37
2.06



AR







IR/IGF1R_1
DIYETDYYR
25
0.69





TSC2_4
GYTISDSAPSR
73
0.69





TSC2_11
YTEFLTGLGR
80
0.69





IRS1_6
HHLNNPPPSQVGLTR
52
0.69





IRS1_11
SVSAPQQIINPIR
57
0.08





IRS1_13
TGIAAEEVSLPR
59
0.23





PTEN_3
NNIDDVVR
208
0.08





PTEN_4
AQEALDFYGEVR
209
0.08





IR_5
TIDSVTSAQELR
16
0.23





IR_12
TVNESASLR
23
0.08





GSK3a_10
VTTVVATLGQGPER
124
0.23





GSK3a_6
SQEVAYTDIK
120
0.69





PRAS40_5
SLPVSVPVWGFK
195
6.17





PRAS40_10
LNTSDFQK
200
0.69





GSK3b_2
DIKPQNLLLDPDTAVLK
129
6.17





GSK3b_6
LLEYTPTAR
133
0.23





AKT1_1
NDGTFIGYK
1
0.23





AKT2_1
SDGSFIGYK
6
0.69





IR/IGF1R_3
DI[Y(PO3H2)]ETDYY
27
0.69



R







TSC2_22
ST[S(PO3H2)]LNERP
91
0.23



K







PRAS40_14
LN[T(PO3H2)]SDFQK
204
0.69









In some embodiments, methods for detecting phosphorylated AKT-mTOR pathway proteins are encompassed. In some embodiments, IP, MS, and IP-MS methods to detect phosphorylated AKT-mTOR pathway proteins are conducted separately from methods to detect total (non-phosphorylated) AKT-mTOR pathway proteins. In some embodiments, the IP and IP-MS methods to detect phosphorylated AKT-mTOR pathway proteins utilize the antibodies of Table 9. In some embodiments, the IP and IP-MS methods to detect non-phosphorylated AKT-mTOR pathway proteins utilize the antibodies of Table 8. In some embodiments, the IP-MS methods to detect phosphorylated AKT-mTOR pathway proteins utilize the antibodies of Table 9 and the peptides of Table 5. In some embodiments, the IP-MS methods to detect non-phosphorylated AKT-mTOR pathway proteins utilize the antibodies of Table 8 and the peptides of Table 5.









TABLE 8







List of non-phosho-antibodies for


multi-plex IP, single-plex IP (+/− MS).











Target
Vendor
IP Antibody







AKT
MILLIPORE
07-416



IGF1R
CELL SIGNALING TECHNOLOGY
3027



IR
MILLIPORE
07-724



IRS1
CELL SIGNALING TECHNOLOGY
2382



mTOR
THERMO FISHER SCIENTIFIC
PA1-518



P70S6K
ABGENT
AP3289g



GSK3a
CELL SIGNALING TECHNOLOGY
4337



GSK3b
THERMO FISHER SCIENTIFIC
MA5-15109



TSC2
THERMO FISHER SCIENTIFIC
MA5-15004



PRAS40
THERMO FISHER SCIENTIFIC
PA5-35143



PTEN
CELL SIGNALING TECHNOLOGY
9188

















TABLE 9







List of antibodies for multi-plex


IP, single-plex IP (+/− MS).









Target
Vendor
IP Antibody





phosphoAKT
CELL SIGNALING TECHNOLOGY
4060


phosphoIGF1R
THERMO FISHER SCIENTIFIC
PA5-35769


phosphoIR
N/A
N/A


phosphoIRS1
MILLIPORE
05-1087


phosphomTOR
CELL SIGNALING TECHNOLOGY
5536


phosphoP70S6K
CELL SIGNALING TECHNOLOGY
9204


phosphoGSK3a
CELL SIGNALING TECHNOLOGY
9327


phosphoGSK3b
CELL SIGNALING TECHNOLOGY
5558


phosphoTSC2
THERMO FISHER SCIENTIFIC
PA5-12845


phosphoPRAS40
CELL SIGNALING TECHNOLOGY
2997


phosphoPTEN
CELL SIGNALING TECHNOLOGY
9551









EXAMPLES

The following examples are provided to illustrate certain disclosed embodiments and are not to be construed as limiting the scope of this disclosure in any way.


Example 1—Immunoprecipitation of AKT-mTOR Pathway Proteins and Discovery-MS

AKT-mTOR pathway proteins play central roles in diseases including cancer. The identification of AKT-mTOR pathway proteins, while desired as a means for monitoring disease progression, and as a tool for scientific research, has been limited in part because of the low abundance of AKT-mTOR pathway proteins, and in part due to a lack of validated methods and reagents. Phosphorylated AKT-mTOR pathway proteins are particularly important to identify and quantify as a measure of protein activation status, and also as markers for disease progression. As shown in FIG. 2, methods and reagents for detecting AKT-mTOR pathway proteins, including phosphorylated proteins, and their protein interactions, were designed and tested. Multiplex immunoprecipitation (IP) to MS (mIP-MS) was assessed for the ability to measure total and phosphorylated AKT-mTOR pathway targets. mIP-MS methods were also compared to existing singleplex immunoassay (Western Blot (WB) and ELISA) and multiplex Luminex assays.


Cell Culture


For all assays, HCT116 (ATCC product#CCL-247), MCF7, (ATCC product#HTB-22) and A549 (ATCC product#CCL-185) cells were grown in Hamm's F-12K media, McCoy's 5A Media, and MEM Media, respectively, with 10% FBS/1×PenStrep to approximately 70-80% confluency. Cells were starved in 0.1% charcoal stripped FBS for 24 hours before stimulation with 100 ng/ml of IGF (CST product#8917SF) for 15 minutes.


Controls


Western Blot (WB), ELISA, and Luminex Assays were used as controls to compare to the IP-MS method described herein. The reagents and methods for Western Blots are summarized in Table 6.









TABLE 6







List of IP to Western Blot validated antibodies for AKT-mTOR Pathway Targets













WB






Target
Antibody
Vendor
Dilution
Gel
Notes





AKT
4691
CELL SIGNALING
(1:1000)  
Tris





TECHNOLOGY

Glycine



phosphoAKT
4051
CELL SIGNALING
(1:1000)  
Tris





TECHNOLOGY

Glycine



IGF1R
3027
CELL SIGNALING
(1:1000)  
Tris Acetate





TECHNOLOGY





phosphoIGF1R
Biotinylated
Abgent
(1:10,000)
Tris Acetate
SA HRP



AP50303



Secondary


IR
3020
CELL SIGNALING
(1:1000)  
Tris Acetate





TECHNOLOGY





phosphoIR
07-841
Millipore
(1:1000)  
Tris Acetate



IRS1
2382
CELL SIGNALING
(1:1000)  
Tris Acetate





TECHNOLOGY





phosphoIRS1
Biotinylated
Millipore
(1:1000)  
Tris Acetate
SA HRP



05-1087



Secondary


mTOR
2983
CELL SIGNALING
(1:1000)  
Tris Acetate





TECHNOLOGY





phosphomTOR
5536
CELL SIGNALING
(1:1000)  
Tris Acetate





TECHNOLOGY





P70S6K
AP3289g
Abgent
(1:1000)  
Tris







Glycine



phosphoP70S6K
9204
CELL SIGNALING
(1:1000)  
Tris





TECHNOLOGY

Glycine



GSK3a
4337
CELL SIGNALING
(1:1000)  
Tris
Clean Blot




TECHNOLOGY

Glycine



phosphoGSK3a
8506
CELL SIGNALING
(1:1000)  
Tris
Clean Blot




TECHNOLOGY

Glycine



GSK3b
12456
CELL SIGNALING
(1:1000)  
Tris
Clean Blot




TECHNOLOGY

Glycine



TSC2
4308
CELL SIGNALING
(1:1000)  
Tris Acetate





TECHNOLOGY





phosphoTSC2
ab52962
Abcam
(1:10,000)
Tris Acetate



PRAS40
AP14275b
Abgent
(1:1000)  
Tris







Glycine



phosphoPRAS40
2997
CELL SIGNALING
(1:1000)  
Tris





TECHNOLOGY

Glycine



PTEN
9188
CELL SIGNALING
(1:1000)  
Tris
Clean Blot




TECHNOLOGY

Glycine



phosphoPTEN
9551
CELL SIGNALING
(1:1000)  
Tris
Clean Blot




TECHNOLOGY

Glycine





Secondary Antibodies: Goat Anti-Rabbit Ab (Thermo Fisher Scientific, PN: 32460), Goat Anti-Mouse Ab (Thermo Fisher Scientific, PN:32430), Pierce High Sensitivity Streptavidin-HRP (Thermo Fisher Scientific, PN: 21130)


SDS-PAGE Gels: NuPAGE 3-8% Tris-Acetate Gel (Thermo Fisher Scientific, PN: EA03752BOX), Novex 4-20% Tris-Glycine Midi Gel (Thermo Fisher Scientific, PN: WT4201BX10)


Clean Blot: Thermo Fisher Scientific, PN: 21232






Reagents for ELISA kits are shown in Table 7.









TABLE 7







ELISA kits for 11 total and 10


phosphorylated AKT-mTOR Pathway Targets










Target
Vendor
Product#
Lot#













Total GSK3B
Cell Signaling Technology
7265
0004


Phospho GSK3β
Cell Signaling Technology
7311
0004


Phospho GSK3β
Life Technologies
KHO0461
16404995B


Total IRS1
Cell Signaling Technology
7328
0011


Phospho IRS1
N/A
N/A
N/A


Total PTEN
Cell Signaling Technology
7882
0005


Phospho PTEN
Cell Signaling Technology
7285
0006


Total PRAS40
Cell Signaling Technology
7331
0003


Phospho PRAS40
Cell Signaling Technology
7327
0004


Total Insulin
Cell Signaling Technology
7069
0006; 0004


Receptor





Phospho Insulin
Cell Signaling Technology
7258
0016; 0015


Receptor





Total IGF1R
R&D Systems
DYC305-2
1324480


Total IGF1R
Abcam
ab100546
GR212867-1


Phospho IGF1R
Cell Signaling Technology
7302
0015


Total GSK3α
R&D Systems
DYC2157-2
1299193


Phospho GSK3α
R&D Systems
DYC4125-2
1300987


Total TSC2
Lifespan Biosciences
LS-F2369
50


Phospho TSC2
Lifespan Biosciences
LS-F1233
49


Total AKT1
Cell Signaling Technology
7170
0048


Phospho AKT1
Cell Signaling Technology
7160
0093


Total mTOR
Cell Signaling Technology
7974
0006


Phospho mTOR
Cell Signaling Technology
7976
0007


Total p7056K
Cell Signaling Technology
7038
0004


Phospho p7056K
Cell Signaling Technology
7063
0005









For Luminex Assays, AKT Pathway (total) Magnetic 7-Plex Panel (Thermo Fisher Scientific, PN: LH00002M), AKT Pathway (phospho) Magnetic 7-Plex Panel (Thermo Fisher Scientific, PN: LH00001M), Milliplex Map Akt/mTOR Phosphoprotein Magnetic Bead 11-Plex Kit (Millipore, PN: 48-611MAG) and Milliplex Map Total Akt/mTOR Magnetic Bead 11-Plex Kit (Millipore, PN: 48-612MAG) were used as recommended in instruction manuals. Luminex MagPix instrument was used to acquire and analyze Luminex assay data.


Immunoprecipitation and MS Sample Preparation


The Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kit (Protein A/G) was used to screen and validate antibodies for 11 total and 10 phosphorylated AKT-mTOR pathway proteins from 500 μg cell lysate. Validated antibodies were biotinylated with the Thermo Scientific™ Pierce Antibody Biotinylation Kit for IP. The Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kit (Streptavidin) was used to perform the single or multiplex IPs for target enrichment. IP samples were processed by an in-solution digestion method where IP eluates were reconstituted in 6M Urea, 50 mM TEAB, pH 8.5 followed by reduction, alkylation and trypsin digestion overnight at 37° C. The digested samples were acidified with TFA before MS analysis.


Liquid Chromatography and Mass Spectrometry


Prior to MS analysis, tryptic digest samples were desalted on-line using the Thermo Scientific™ Acclaim™ PepMap 100 C18 Trap Column. For discovery MS, the samples were analyzed by nanoLC-MS/MS using a Thermo Scientific™ Dionex™ UltiMate™ 3000 RSLCnano System and Thermo Scientific™ Q Exactive™ HF Hybrid Quadrupole-Orbitrap Mass Spectrometer. For targeted MS, the samples were analyzed using the UltiMate 3000 RSLCnano System and the Thermo Scientific™ TSQ™ Vantage™ Mass Spectrometer (SRM mode) or the Thermo Scientific™ Q Exactive™ HF Hybrid Quadrupole-Orbitrap Mass Spectrometer (PRM mode).


MS Data Analysis


Discovery MS data were analyzed with Thermo Scientific™ Proteome Discoverer™ 1.4 to assess percent sequence coverage, unique peptides, MS1 intensities, spectral counts and PTMs. The Proteome Discoverer software searches were executed using the Uniprot human protein database. Tryptic peptides with highest MS1 intensity and relevant phosphorylation sites were selected from the discovery data for targeted assay development. For targeted MS data analysis, Thermo Scientific™ Pinpoint software and Skyline software (University of Washington) were used to measure limit of quantitation (LOQ) from the calibration curve and target analyte concentration from unknown samples.


Results


As shown in FIG. 3, AKT-mTOR pathway proteins were immunoprecipitated from unstimulated and IGF-stimulated A549 lysate with Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kits (Protein A/G or Streptavidin) for MS analysis. A variety of antibodies were screened to determine effectiveness in both ability to IP AKT-mTOR pathway proteins, and also for their usefulness when combined with MS. Table 1 (above) provides a list of antibodies validated for use in the IP-MS methods. Table 2 (above) provides a list of antibodies tested, but found to be less successful.


Higher numbers of unique peptides were identified in IP enriched samples as compared to neat (non-IP-enriched) lysate. See FIG. 3. Protein isoforms and interacting protein partners were identified for AKT, IGF1R and mTOR targets. Relevant phosphorylation sites were detected for AKT1, AKT2, mTOR, IGF1R and PRAS40. Candidate quantitative peptides were selected for targeted MS assay development.


Limits of detection (LOD) and lower limits of quantification (LLOQ) were analyzed for twelve AKT-mTOR pathway proteins, including AKT2, AKT1, mTOR, IGF1R, IR, PRAS40, p70S6K, TSC2, PTEN, GSK3alpha, GSK3beta, and IRS1. Results are presented in FIG. 4. The assay dynamic range, representing the concentration range between the lower to upper limits of quantification (LLOQ to ULOQ), is the range where protein concentration is measurable with acceptable levels of accuracy and precision. To ensure linearity of the measurement, for each internal standard peptide the linear signal-to-abundance range (LLOQ and ULOQ) was determined from dilution series experiments spanning concentrations of 500-0.08 fmol on column, spiked into a constant light peptide at 36 fmol and 200 ng of equimolar concentration of 6 proteins digest.


Example 2—Multiplex IP of AKT-mTOR Pathway Proteins and Multiplex MS

Eleven total and ten phosphorylated AKT-mTOR pathway protein targets were enriched simultaneously from unstimulated and IGF stimulated MCF7 lysates with biotinylated antibodies and Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kit (Streptavidin). MCF7 cells were starved in 0.1% charcoal stripped FBS for 24 hours before stimulation with 100 ng/ml of IGF for 15 minutes. Validated IP-MS antibodies are biotinylated for 11 total and 10 phosphorylated AKT-mTOR pathway targets using the Thermo Scientific™ Pierce Antibody Biotinylation Kit for IP (PN: 90407) as recommended in instruction manual. 1 μg of each biotinylated antibody for 11 total targets were added simultaneously to 1000 μg of control and IGF stimulated MCF7 cell lysate in duplicate. 1 μg of each biotinylated antibody for 10 total targets were added simultaneously to 1000 μg of control and IGF stimulated MCF7 cell lysate in duplicate. IP was performed as recommended in the Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kit (Streptavidin) (PN: 90408) with the following modification. 5 microgram of streptavidin magnetic beads per microgram of biotinylated antibody concentration was used for multiplex IP.


IP samples were processed by an in-solution digestion method where IP eluates were reconstituted in 6M Urea, 50 mM TEAB, pH 8.5 followed by reduction (5 mM TCEP for 30 minutes at 35° C.), alkylation (20 mM Iodoacetamide in dark at room temperature for 30 minutes) and trypsin digestion overnight at 37° C. The digested samples were acidified with 3.5 μL of 10% TFA before discovery MS analysis. For discovery MS, the samples were analyzed by nanoLC-MS/MS using a Thermo Scientific™ Dionex™ UltiMate™ 3000 RSLCnano System and Thermo Scientific™ Q Exactive™ HF Hybrid Quadrupole-Orbitrap Mass Spectrometer. Briefly, the digested samples were cleaned on-line using the C18 trap column (Thermo Fisher Scientific, PN: 164564) followed by reversed-phase separation using the analytical C18 column (75 μm i.d.×15 cm, nanoViper, 3 μm particle size, Thermo Fisher Scientific, PN: ES800) with a 2-30% gradient of Buffer B using Buffer A (0.1% formic acid) and Buffer B (0.1% formic acid/99.9% acetonitrile) at 0.300 μL/min.



FIG. 5 shows that the IP-nanoLC-MS/MS analysis was able to identify 11 proteins in the multiplex phosphor-assay, and 12 proteins for multiplex total assay. MS analysis of multiplex total assay identified interacting proteins (PIK3R1, PIK3R2, PIK3CB, PIK3CA, GSKIP and TSC1) of AKT-mTOR Pathway Targets. Tables 8 and 9 provide listings of the antibodies used in this multiplex IP.


Next the ability of IP-MS to quantify sub-fmol concentrations of AKT-mTOR pathway proteins via the disclosed IP-MS methods was tested. As shown in FIG. 6, a multiplex IP enrichment of AKT (Total & Phospho), IR, p70S6K, mTOR, and GSK3α was performed from unstimulated and IGF stimulated A549 and HCT116 lysates with Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kit (Streptavidin). A549 and HCT116 cells were starved in 0.1% charcoal stripped FBS for 24 hours before stimulation with 100 ng/ml of IGF for 15 minutes. Validated IP-MS antibodies are biotinylated for Total AKT, Phospho AKT, IR, p70S6K, mTOR, and GSK3α pathway targets using the Thermo Scientific™ Pierce Antibody Biotinylation Kit for IP (PN: 90407) as recommended in instruction manual. 1 μg of each biotinylated antibody was added simultaneously to 1000 μg of control and IGF stimulated A549 and HCT116 cell lysates in duplicate. IP was performed as recommended in the Thermo Scientific™ Pierce MS-Compatible Magnetic IP Kit (Streptavidin) (PN: 90408) with the following modification. 5 microgram of streptavidin magnetic beads per microgram of biotinylated antibody concentration was used for multiplex IP. IP samples were processed by an in-solution digestion method where IP eluates were reconstituted in 6M Urea, 50 mM TEAB, pH 8.5 followed by reduction (5 mM TCEP for 30 minutes at 35° C.), alkylation (20 mM Iodoacetamide in dark at room temperature for 30 minutes) and trypsin digestion overnight at 37° C. The digested samples were acidified with 3.5 μL of 10% TFA before discovery MS analysis. Internal standard peptides were spiked in digested IP samples to make final volume of 6.66 fmol/ul. For targeted MS, the samples were analyzed by nanoLC-PRM/MS using a Thermo Scientific™ Dionex™ UltiMate™ 3000 RSLCnano System and Thermo Scientific™ Q Exactive™ HF Hybrid Quadrupole-Orbitrap Mass Spectrometer. Briefly, the digested samples were cleaned on-line using the C18 trap column (Thermo Fisher Scientific, PN: 164564) followed by reversed-phase separation using the analytical C18 column (75 pin i.d.×15 cm, nanoViper, 3 μm particle size, Thermo Fisher Scientific, PN: ES800) with a 2-30% gradient of Buffer B using Buffer A (0.1% formic acid) and Buffer B (0.1% formic acid/99.9% acetonitrile) at 0.300 μL/min. Total targets were quantified in low to sub-fmol concentrations by nanoLC-PRM/MS. Up-regulation of phospho AKT was seen after IGF stimulation in both A549 and HCT116 cell lines. The slight decrease in concentrations for total AKT, IR, mTOR, GSK3α and p70S6K targets was observed after IGF stimulation in both A549 and HCT116 cells.


Example 3—Benchmarking

Next, comparison of mIP-tMS assays with current immunoassay techniques to quantitate AKT-mTOR pathway targets from unstimulated and IGF stimulated A549, HCT116 and MCF7 lysates were performed. Western Blot, ELISA, and Luminex assays were performed as described above and according to manufacturer's instructions. mIP-tMS was performed as in Example 2.



FIGS. 7A-7D show quantitation of total AKT. FIGS. 7E-7H show quantitation of phosphorylated IGF1R across all 4 techniques. Lower correlation was observed across techniques. The lower correlation could be due to different antibodies used or each assay and antibody specificity. Up-regulation in phosphorylated IGF1R observed after IGF stimulation in 3 of 4 techniques. Western blot for phosphor IGF1R showed no significant differences in control and IGF stimulated cell lysates.


A summary of AKT-mTOR pathway proteins that were identified and quantified using the IP-MS methods described herein is provided in FIG. 8. Most of the AKT-mTOR pathway targets were not identified in discovery MS and quantitated by targeted MS (PRM or SRM) without enrichment by immunoprecipitation.


Immunoprecipitation using particular selected antibodies resulted in a higher yield of AKT-mTOR pathway target proteins and less non-specific binding proteins than MS alone. IP-MS assay was also more successful than other commercially available non-MS assays. Furthermore, IP to MS analysis of total and phosphorylated AKT-mTOR pathway proteins enabled identification of multiple isoforms, relevant protein interactions and phosphorylation sites. Total and phosphorylated mIP-tMS assays allowed simultaneous quantitation of 12 total and 11 phosphorylated AKT-mTOR pathway proteins in the low to sub-fmol range from unstimulated and IGF stimulated A549, HCT116 and MCF7 cell lysates. The benchmarking of mIP-tMS assays showed moderate correlation for quantitation of total and phosphorylated target relative abundance compared to WB, ELISA and Luminex assays. The low concordance for a few targets is possibly due to differences in the specificity of antibodies used for each assay. Major advantages of the MS-based assay are high confidence in target identity coupled with simultaneous quantitation of multiple targets, interacting proteins and their phosphophorylated forms.


Example 4—Tissue Sample Validation

Tissue lysis protocol was optimized for IP-MS application. Briefly, 50-100 mg of human and murine tissue samples were washed with 5 mL 1× cold PBS three times. Tissue samples was minced in 5 mL 1× cold PS using scissor followed by homogenization in IP lysis buffer (Thermo Fisher Scientific PN: 87788) and electronic Polytron Handheld Tissue Tearer. Homogenized tissue samples were passed through tissue strainer (Thermo Fisher Scientific PN: 87791) to prepare tissue lysates before IP. To validate the IP-MS method in murine and human tissue lysate, eleven total and ten phosphorylated AKT-mTOR pathway protein targets were enriched simultaneously from normal mouse lung tissue lysate, normal mouse kidney tissue lysate, and normal human lung tissue lysate as per Example 2. A549 cell lysate was used as a non-tissue control. As shown in Table 10, the IP-MS method described herein is capable of validating AKT-mTOR pathway proteins in murine and human tissue lysate in addition to cell lysate. Seven out of eleven AKT-mTOR pathway protein targets were identified in normal human lung tissue, and nine out of eleven AKT-mTOR pathway protein targets were identified for normal mouse kidney tissue using our IP-MS method.









TABLE 10







11-plex total IP-MS assay validating tissue lysate.


Intensities of top 3 peptides











Total Targets
A549 Cell Line
Mouse Lung
Human Lung
Mouse Kidney





AKT1
2.0E+08
1.2E+08
2.6E+06



PRAS40
9.8E+08
1.0E+08
2.3E+07
2.5E+07


GSK3b
8.0E+08
8.3E+08
L2E+08
3.4E+08


IGF1R
5.4E+08
7.4E+07
1.2E+07
1.4E+08


IRS1
7.2E+07
7.1E+06




IR1
2.1E+08
6.2E+07
3.4E+07
1.5E+08


mTOR
9.4E+07
1.3E+07
2.2E+07
6.7E+07


p70S6K
6.4E+07
3.8E+08

1.8E+08


TSC2
9.1E+07
1.9E+07

3.7E+07


PTEN
6.1E+07
5.3E+07
2.4E+07
1.3E+08


GSk3a
2.8E+08
1.4E+08

9.2E+07








Claims
  • 1. A method for detecting AKT-mTOR pathway proteins, comprising a. treating a biological sample with at least one antibody capable of immunoprecipitating AKT-mTOR pathway protein(s) from a biological sample;b. digesting the immunoprecipitated target protein(s);c. assaying the digested protein(s) via mass spectrometry to determine the presence of at least one peptide for AKT-mTOR pathway protein(s), wherein the at least one peptide for AKT-mTOR pathway protein(s) is less than 40 amino acids in length and further wherein the at least one peptide comprises one or more of: i. a peptide comprising SEQ ID NO: 106 corresponding to MTOR_14,ii. a peptide comprising SEQ ID NO: 96 corresponding to mTOR_4,iii. a peptide comprising SEQ ID NO: 101 corresponding to mTOR_9,iv. a peptide comprising SEQ ID NO: 110 corresponding to MTOR_18,v. a peptide comprising SEQ ID NO: 157 corresponding to p70S6K_1,vi. a peptide comprising SEQ ID NO: 159 corresponding to p70S6K_3, andd. detecting one or more AKT-mTOR pathway protein(s) in the sample.
  • 2. The method of claim 1, further comprising determining the quantity of AKT-mTOR pathway protein.
  • 3. The method of claim 1, wherein the AKT-mTOR pathway protein is phosphorylated.
  • 4. The method of claim 1, wherein the at least one AKT-mTOR pathway peptide comprises two or more peptides chosen from SEQ ID NOS: 106, 96, 101, 110, 157, and 159.
  • 5. The method of claim 1, wherein the biological sample is human.
  • 6. The method of claim 1, wherein the antibody to detect phosphorylated AKT-mTOR pathway protein comprises an antibody that binds to phosphorylated AKT, phosphorylated IGF1R, phosphorylated IRS, phosphorylated IRS1, phosphorylated mTOR, phosphorylated P70S6K, phosphorylated GSK3a, phosphorylated GSK3b, phosphorylated TSC2, phosphorylated PRAS40, or phosphorylated PTEN.
  • 7. The method of claim 1, wherein the antibody to detect non-phosphorylated AKT-mTOR pathway protein comprises an immunoprecipitation (IP) antibody that binds to AKT, IGF1R, IR, IRS1, mTOR, P70S6K, GSK3a, GSK3b, TSC2, PRAS40, or PTEN.
  • 8. The method of claim 1, wherein the peptide is modified with a detectable label, wherein the detectable label comprises an isotope selected from 13C, 15N, 2H and 18O.
  • 9. The method of claim 1, wherein the antibody is chosen from an antibody that binds to AKT1, AKT (pan), AKT2, phosphorylated AKT2 (pSer474), phosphorylated AKT (pSer473), phosphorylated IGF-1R (Tyr1161/Tyr1165/Tyr1166), phosphorylated IGF1 Receptor (IGF1R) pTyr1158+1162+1163, phosphorylated IGF1R pTyr1161, phosphorylated IGF-I Receptor β (Tyr1131), phosphorylated Insulin Receptor β (Tyr1146), IGF-I/Insulin Receptor β, INSR/Insulin Receptor, α-Insulin Receptor β subunit, INSR/Insulin Receptor alpha, phosphorylated Insulin Receptor (Y972), IRS1, phosphorylated IRS1 (pSer312), phosphorylated IRS1 (Ser307 mouse/Ser312 human), phosphorylated IRS-1 (pSer1101), mTOR, phosphorylated mTOR (pSer2448), S6K, S6K1, phosphorylated p70 S6 Kinase (pThr389/pThr412), phosphorylated p70 S6 Kinase (pThr389), phosphorylated p70 S6 Kinase (pThr421/pSer424), phosphorylated GSK-3α/β (pSer21/pSer9), GSK3α, phosphorylated GSK-3α (Ser21), GSK-3β, phosphorylated GSK-3β (pSer9), phosphorylated Tuberin/TSC2 (pSer939), TSC2, S6 ribosomal protein, phosphorylated S6 ribosomal protein (pSer235+236), PRAS40, phosphorylated PRAS40 (pThr246), phosphorylated PTEN (pSer380), or PTEN.
  • 10. The method of claim 9, wherein the antibody is capable of immunoprecipitating more than one AKT-mTOR pathway protein.
  • 11. The method of claim 1, wherein a first antibody is capable of immunoprecipitating a phosphorylated AKT-mTOR pathway protein, and a second antibody is capable of immunoprecipitating a non-phosphorylated version of the AKT-mTOR pathway protein precipitated by the first antibody.
  • 12. The method of claim 1, wherein step a) comprises treating the sample with a labelled antibody capable of binding to the pathway protein to provide a labelled antibody-protein conjugate; and binding the labelled antibody-protein conjugate with a capture agent capable of binding to the labelled antibody to isolate the target protein from the sample.
  • 13. The method of claim 1, wherein the quantity of an AKT-mTOR pathway protein is determined by adding an internal standard peptide of known amount to the digested protein prior to mass spectrometry, wherein the internal standard peptide has the same amino acid sequence as the AKT-mTOR pathway peptide, and is detectably labeled, and determining the quantity of an AKT-mTOR pathway peptide by comparison to the internal standard.
  • 14. The method of claim 1, wherein the quantity of an AKT-mTOR pathway protein is determined by a method comprising comparing an amount of the AKT-mTOR pathway peptide to an internal standard peptide of known amount, wherein both the peptide in the biological sample and the internal standard peptide are chosen from SEQ ID NOS: 106, 96, 101, 110, 157, and 159.
  • 15. The method of claim 13, wherein the internal standard peptide is chosen from SEQ ID NOS: 106, 96, 101, 110, 157, and 159:1.
  • 16. The method of claim 1, wherein the digesting comprises a protease or chemical digest.
  • 17. The method of claim 1, wherein the AKT-mTOR pathway protein is selected from RAC-alpha serine/threonine-protein kinase (AKT1), RAC-beta serine/threonine-protein kinase (AKT2), insulin receptor (INSR), insulin-like growth factor 1 receptor (IGF1R), insulin receptor substrate 1 (IRS1), tuberin (TSC2), serine/threonine-protein kinase mTOR (mTOR), glycogen synthase kinase-3 alpha (GSK3a), glycogen synthase kinase-3 beta (GSK3b), GSK3a/GSK3b, ribosomal protein S6 kinase beta-1 (p70S6K; RPS6KB1), 40S ribosomal protein S6 (RPS6), proline-rich AKT1 substrate 1 (PRAS40; AKT1S1), and phosphatidylinositol 3,4,5-triphosphate 3-phosphatase and dual-specificity protein phosphatase (PTEN).
  • 18. The method of claim 2, wherein the lower limit of quantification is within the range of about 0.05-0.75 fmol.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 of International Application No. PCT/US2017/022062, filed Mar. 13, 2017, which claims the benefit of priority of U.S. Provisional Patent Application No. 62/308,051, filed Mar. 14, 2016, which is incorporated by reference herein in its entirety for all purposes.

PCT Information
Filing Document Filing Date Country Kind
PCT/US2017/022062 3/13/2017 WO
Publishing Document Publishing Date Country Kind
WO2017/160698 9/21/2017 WO A
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Related Publications (1)
Number Date Country
20190086420 A1 Mar 2019 US
Provisional Applications (1)
Number Date Country
62308051 Mar 2016 US