Comparison of the modes of action of Ca2+ ionophore A23187 and thrombin in protein kinase C activation in human platelets

FEBS Letters

Takai, Yoshimi²  Matsuo, Tamotsu¹  Sano, Kimihiko¹  Kawahara, Yasuhiro¹  Fukuzaki, Hisashi¹  Nakamura, Hajime¹  Kaibuchi, Kozo² 

[1] Departments of Pediatrics, Internal Medicine (1st division), Kobe 650, Japan;Departments of Biochemistry, Kobe University School of Medicine, Kobe 650, Japan

关键词: Platelet;    Ca2+ ionophore;    Protein kinase C;    Protein phosphorylation;    Diacylglycerol;    Cytoplasmic Ca2+;    PAF;    platelet-activating factor;    MLC;    myosin light chain;   

DOI  :  10.1016/0014-5793(85)80031-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In human platelets, the Ca²⁺ ionophore A23187 stimulated the phosphorylation of a 40 kDa protein and myosin light chain (MLC) to the same extents as those induced by thrombin, but the doses of A23187 for 40 kDa protein phosphorylation were higher than those for MLC phosphorylation, although the doses of thrombin for both reactions were nearly the same. Moreover, A23187 produced much less diacylglycerol than thrombin. However, the sites of the 40 kDa protein phosphorylated by the action of A23187 and thrombin were identical, and the 40 kDa protein phosphorylation induced by A23187 and thrombin was inhibited by tetracaine, an inhibitor for protein kinase C. Neither A23187 nor thrombin induced the production of a catalytic fragment of protein kinase C which might be generated by limited proteolysis with Ca²⁺-dependent protease. These results indicate that A23187 induces protein kinase C activation which phosphorylates the 40 kDa protein, but higher doses of A23187 are required for the activation of this enzyme than for the activation of MLC kinase.

【 授权许可】

Unknown