title: Various proteins modulate the kinase activity of the insulin receptor.
abstract: Previous studies of the substrate specificity of the purified insulin receptor tyrosine kinase using synthetic random polymers have demonstrated that the receptor kinase phosphorylates poly (Glu, Tyr) 4:1 but not poly (Glu, Tyr) 1:1. In the present study, insulin treatment of Chinese hamster ovary cells overexpressing the human insulin receptor was found to stimulate the ability of their membrane extracts to phosphorylate poly (Glu, Tyr) 1:1. It was concluded that this activity was due to the receptor itself because: 1) it was precipitated with a monoclonal antibody to the receptor; 2) the addition of various membrane extracts to purified insulin receptor preparations stimulated the ability of these preparations to phosphorylate poly (Glu, Tyr) 1:1; and 3) certain purified proteins, including bovine serum albumin and casein, were also capable of stimulating the purified receptor to phosphorylate poly (Glu, Tyr) 1:1. The effect of albumin was dose-dependent; 0.5 and 10 mg/ml bovine serum albumin stimulated the phosphorylation of poly (Glu, Tyr) 1:1 by 2- and 230-fold, respectively. In contrast, albumin had no effect on the phosphorylation of poly (Glu, Tyr) 4:1. These results indicate that the activity of the insulin receptor kinase on certain substrates can be modulated by the presence of other proteins.
authors: Department of Pharmacology, Stanford University School of Medicine, California 94305.
authors: K
authors: K
authors: Yonezawa
authors: R A
authors: RA
authors: Roth
mesh_terms: D000818:Animals; D002364:Caseins / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D006224:Cricetinae; D007163:Immunosorbent Techniques; D007328:Insulin / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology*; D011972:Receptor, Insulin; D012710:Serum Albumin, Bovine / Q000494:pharmacology
chemical_list: D002364:Caseins; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D011506:Proteins; D012710:Serum Albumin, Bovine; C027606:L-glutamic acid-L-tyrosine copolymer; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin