小肠平滑肌胰岛素受体的特征及其蛋白激酶活性

 本实验对狗小肠平滑肌中胰岛素受体的结构和特征进行了分析研究。通过麦胚凝集素琼脂糖和两次Sepharose-CL-6B凝胶层析从平滑肌中纯化胰岛素受体,达到电泳纯。SDS-聚丙烯酰胺凝胶电泳证明胰岛素受体是由两个亚基组成的,分子量分别为135kD和90kD。磷酸化实验证明平滑肌胰岛素受体具有胰岛素依赖性蛋白激酶活性,能催化自身的β亚基磷酸化和底物的磷酸化。Scatchard分析表明胰岛素和受体的结合呈(?)协同效应,最大结合率为13μg胰岛素/mg蛋白质。

Characterization of Subunit Structure and Protein Kinase Activity of Insulin Receptor Purified from Smooth Muscle of Small Intestine

Subunit structure and protein kinase activity of insulin receptor of canine small intestinal smooth muscle have been studied. The receptor was purified to homogeneity by affinity chromatography on WGA-sepharose column and two sequential gel filtration on Sepharose-CL-6B column. Just as the α and β subunits of the insulin receptor in other tissues, the purified receptor showed two major bands with Mr 135000 and 90000, respectively, on SDS-polyacrylamide electrophoresis. Insulin stimulates autosphorylation of the β -subunit and the phosphorylation of hist-one H2b. Scatchard analysis showed that the competitive binding of insulin to receptor was negatively cooperative and the maximal binding capacity was 13μg/mg protein.