IRS-1 Activates Phosphatidylinositol 3'-Kinase by Associating with src Homology 2 Domains of p85

• Published in: Proceedings of the National Academy of Sciences - PNAS 1992-11, Vol.89 (21), p.10350-10354
• Main Authors: Myers, Martin G., Backer, Jonathan M., Sun, Xiao Jian, Shoelson, Steven, Hu, Patrick, Schlessinger, Joseph, Yoakim, Monique, Schaffhausen, Brian, White, Morris F.
• Format: Article
• Language: English
• Subjects: 3T3 Cells; activation; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Animals; Antibodies; Binding Sites; Biological and medical sciences; Cellular biology; CHO Cells; Cloning, Molecular; Cricetinae; Diabetes; DNA - genetics; domains; Enzyme Activation; Enzymes; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Genes, src; Glutathione Transferase - pharmacology; Goods and services tax; Insulin; insulin receptor substrate 1; Insulin Receptor Substrate Proteins; IRS-1 protein; Kinetics; Macromolecular Substances; Medical research; Mice; Molecular Sequence Data; Molecular Weight; phosphatidylinositol 3'-kinase; Phosphatidylinositol 3-Kinases; Phosphatidylinositols; Phosphopeptides - pharmacology; Phosphoproteins - metabolism; Phosphorylation; Phosphotransferases - metabolism; Physiological regulation; Protein-Tyrosine Kinases - metabolism; Proteins; rats; Receptor, Insulin - metabolism; Receptors; Recombinant Fusion Proteins - pharmacology; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; Substrate Specificity; Transferases; tyrosine
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.89.21.10350

IRS-1 is an insulin receptor substrate that undergoes tyrosine phosphorylation and associates with the phosphatidylinositol (PtdIns) 3'-kinase immediately after insulin stimulation. Recombinant IRS-1 protein was tyrosine phosphorylated by the insulin receptor in vitro and associated with the PtdIns 3'-kinase from lysates of quiescent 3T3 fibroblasts. Bacterial fusion proteins containing the src homology 2 domains (SH2 domains) of the 85-kDa subunit (p85) of the PtdIns 3'-kinase bound quantitatively to tyrosine phosphorylated, but not unphosphorylated, IRS-1, and this association was blocked by phosphotyrosine-containing synthetic peptides. Moreover, the phosphorylated peptides and the SH2 domains each inhibited binding of PtdIns 3'-kinase to IRS-1. Phosphorylated IRS-1 activated PtdIns 3'-kinase in anti-p85 immunoprecipitates in vitro, and this activation was blocked by SH2 domain fusion proteins. These data suggest that the interaction between PtdIns 3'-kinase and IRS-1 is mediated by tyrosine phosphorylated motifs on IRS-1 and the SH2 domains of p85, and IRS-1 activates PtdIns 3'-kinase by binding to the SH2 domains of p85. Thus, IRS-1 likely serves to transmit the insulin signal by binding and regulating intracellular enzymes containing SH2 domains.