Insulin-induced tyrosine-phosphorylation in intact rat adipocytes

Insulin-induced tyrosine-phosphorylation in intact isolated rat adipocytes was studied using immunoblotting method with anti-phosphotyrosine antibodies. Insulin-stimulated adipocytes were solubilized with Triton X-100. The lysate was incubated with wheat germ agglutinin, then with hydroxylapatite. Insulin stimulated tyrosinephosphorylation of a 95 KDa protein which adsorbs to wheat germ agglutinin and appears to be the β-subunit of the insulin receptor. Among the proteins adsorbed to hydroxylapatite, tyrosine-phosphorylation of 170 KDa and 60 KDa proteins was stimulated. 170 KDa was also stimulated by polyclonal anti-insulin receptor antibodies B-10 Ig G, IGF-I and H₂O₂ . The detection of these proteins in rat adipocytes may lead to the elucidation of a common signal transduction pathway in insulin-responsive cells.