Ido M, Ogawa H, Kato S, Hayashi K, Suzuki K
Department of Molecular Pathobiology, Mie University School of Medicine, Japan.
Pol J Pharmacol. 1996 Jan-Feb;48(1):105-7.
In order to examine a possible role of protein kinases in the signal transduction of platelet activation, thrombin-stimulated human platelets were analyzed for protein kinase activity with a denaturation/renaturation method. Treatment of platelets with thrombin resulted in a rapid activation of a 33-kDa protein kinase (PK33) using casein as an in vitro substrate. The concentration of thrombin to activate PK33 was proportional to that required to induce platelet aggregation. PK33 was also activated by a thrombin receptor agonist peptide, but not by hirudin-treated or diisopropylphosphate-inactivated thrombin. Phosphoamino acid analysis showed that PK33 is a serine/threonine kinase. Comparative analysis using specific substrate and inhibitors revealed that PK33 is distinct from casein kinase I, casein kinase II, P34cdc2, and mitogen activated protein kinase. These findings suggest that platelet activation mediated by thrombin receptor requires PK33 activation.
为了研究蛋白激酶在血小板激活信号转导中的可能作用，采用变性/复性方法分析了凝血酶刺激的人血小板的蛋白激酶活性。用酪蛋白作为体外底物，凝血酶处理血小板可导致一种33 kDa蛋白激酶（PK33）迅速激活。激活PK33的凝血酶浓度与诱导血小板聚集所需的浓度成正比。凝血酶受体激动肽也可激活PK33，但水蛭素处理的或二异丙基磷酸酯灭活的凝血酶则不能激活PK33。磷酸氨基酸分析表明PK33是一种丝氨酸/苏氨酸激酶。使用特异性底物和抑制剂的比较分析显示，PK33不同于酪蛋白激酶I、酪蛋白激酶II、P34cdc2和丝裂原活化蛋白激酶。这些发现提示，凝血酶受体介导的血小板激活需要PK33的激活。
