Borowski P, Kornetzky L, Laufs R
Institut für Medizinische Mikrobiologie und Immunologie Universitätsklinik Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
J Biochem. 1998 Mar;123(3):380-5. doi: 10.1093/oxfordjournals.jbchem.a021948.
Treatment of A431 cell membranes with trypsin or Streptomyces griseus proteinase results in degradation of the EGF-R and the concomitant generation of an active kinase with a molecular mass of 42 kDa (42 kDa kinase). To investigate the biochemical properties of the 42 kDa kinase, the EGF-R was immunoaffinity-purified from the A431 cell membranes and the kinase proteolytically generated. The proteolysis of EGF-R changes both the Vmax and the Michaelis constants of substrates. These substrates determine the extent of the changes of the parameters. The 42 kDa kinase is less responsive to polyions as regulators of kinase activity and is less efficiently inhibited by genistein and tyrphostin. The experiments described here point to a role of the extracatalytic domains in determining the substrate specificity and regulation of kinase activity.
用胰蛋白酶或灰色链霉菌蛋白酶处理A431细胞膜会导致表皮生长因子受体（EGF-R）降解，并同时产生一种分子量为42 kDa的活性激酶（42 kDa激酶）。为了研究42 kDa激酶的生化特性，从A431细胞膜中免疫亲和纯化EGF-R，并通过蛋白水解产生激酶。EGF-R的蛋白水解会改变底物的最大反应速度（Vmax）和米氏常数。这些底物决定了参数变化的程度。42 kDa激酶作为激酶活性调节剂对聚离子的反应较小，并且受金雀异黄素和 tyrphostin 的抑制效率较低。此处描述的实验表明，催化外结构域在确定底物特异性和激酶活性调节中起作用。
