Characterization of the insulin receptor kinase purified from human placental membranes.

摘要: The insulin receptor purified from human placenta by sequential affinity chromatography on wheat germ agglutinin- and insulin-Sepharose to near homogeneity retained tyrosine-specific protein kinase activity. This specifically catalyzed the incorporation of 32P [gamma-32P]ATP into not only beta-subunit but also histone H2B, a synthetic peptide which is sequentially similar site tyrosine phosphorylation in pp60src (a gene product Rous sarcoma virus) antibodies present sera obtained three rabbits bearing tumors induced virus. In each case, occurred exclusively residues. Insulin stimulated these substrates 3- 5-fold. Kinetic analysis using indicated that acted increasing Vmax about 3.1 9.5 nmol X mg-1 min-1, whereas value Km for peptide, 1.5 mM, was significantly changed. weakly casein, alpha-S-casein, actin, tyrosine-containing analogue serine-containing used commonly as substrate cyclic AMP-dependent kinases. These data show displays specificity toward exogenous observed activity associated with epidermal growth factor. suggest catalytic sites kinases are activates its Vmax.