TI - A mutant insulin receptor induces formation of a Shc-growth factor receptor bound protein 2 ( Grb2 ) complex and p21ras-GTP without detectable interaction of insulin receptor substrate 1 ( IRS1 ) with Grb2 . Evidence for IRS1-independent p21ras-GTP formation . AB - The activation of p21ras by receptor tyrosine kinases involves the translocation of the growth factor receptor bound protein 2-mammalian son of sevenless protein ( Grb2-SOS ) complex to the plasma membrane where p21ras is localized . Insulin receptors induce p21ras-GTP formation by two possible mechanisms : tyrosine phosphorylation of insulin receptor substrate 1 ( IRS1 ) and its subsequent association with Grb2 , or Shc phosphorylation and its subsequent association with Grb2 . We investigated the contribution of the major tyrosine autophosphorylation sites Tyr1158 , Tyr1162 , and Tyr1163 of the insulin receptor to IRS1.Grb2 and Shc.Grb2 association and the formation of p21ras-GTP . Chinese hamster ovary-derived cell lines were used overexpressing mutant insulin receptors in which the major tyrosine autophosphorylation sites were stepwise replaced by phenylalanines . In cell lines expressing wild type or mutant Y1158F , Y1162 , Y1163 (FYY) receptors , insulin stimulated tyrosine phosphorylation of IRS1 and Shc and the formation of IRS1.Grb2 and Shc.Grb2 protein complexes , together with an increase in p21ras-GTP . Cell lines expressing mutant Y1158 , Y1162F , Y1163F (YFF) receptors showed insulin-induced tyrosine phosphorylation of Shc , Shc.Grb2 complex formation , and p21ras-GTP formation , whereas tyrosine phosphorylation of IRS1 was strongly decreased and formation of IRS1.Grb2 complexes was undetectable . The activity of FYY and YFF receptors to mediate p21ras-GTP formation correlated with their activity to induce Shc phosphorylation and Shc.Grb2 association . The mutant insulin receptors Y1158F , Y1162F , Y1163 and Y1158F , Y1162F , Y1163F were inactive in inducing any of these responses . We conclude that phosphorylation of Tyr1158 and Tyr1162 of the insulin receptor is linked to distinct post - receptor processes and that YFF receptors generate p21ras-GTP via the Shc.Grb2 pathway rather than one involving IRS1.Grb2 interaction .