Insulin stimulated tyrosine phosphorylation of SHC, a SH2 containing protein, was demonstrated in Chinese hamster ovary cells overexpressing the insulin receptor by immunoblotting with anti-phosphotyrosine antibodies and in vivo labeling. Insulin induced tyrosine phosphorylation of SHC occurred very rapidly (within 1 min) with a dose curve which paralleled the autophosphorylation of the insulin receptor. Phosphorylation of SHC appeared to occur to a high stoichiometry since insulin induced the majority of SHC to shift to a higher molecular weight. The tyrosine phosphorylated SHC was not bound by the GTPase activating protein of Ras although a distinct 62 kDa tyrosine phosphorylated protein was found to be associated in the same experiments. It also was not bound to the insulin receptor, phosphatidylinositol 3-kinase or insulin receptor substrate-1. © 1993 Academic Press, Inc.
