IRS-1 activates phosphatidylinositol 3′-kinase by associating with src homology 2 domains of p85

Martin G. Myers, Jonathan M. Backer, Xiao Jian Sun, Steven Shoelson, Patrick Hu, Joseph Schlessinger, Monique Yoakim, Brian Schaffhausen, Morris F. White

Research output: Contribution to journalArticlepeer-review

433 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)10350-10354
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number21
StatePublished - 1992
Externally publishedYes

ASJC Scopus subject areas

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