Department of Surgery 11, Osaka University School of Medicine, 2-2 Yamadaoka Suita, Osaka, 565, Japan.
Platelets. 1995;6(4):185-9. doi: 10.3109/09537109509078452.
Calpain, a Ca(2+) activated intracellular protease and its endogeneous protein inhibitor, calpastatin are abundant in platelets. The structure and enzymological properties of calpain, including its isozymes, and of calpastatin in platelets have been fully characterized. Also, platelet calpain has been shown to cleave various endogeneous polypeptides. However, the mode of activation and the physiological function of platelet calpains have not been clarified. Our recent investigations on platelet calpains with cell permeable calpain antagonists and specific antibodies reveal that calpains are not involved in the early phases of platelet activation such as shape change and aggregation, but in the later phases of platelet activation such as cytoskeletal reorganization and Ca(2+) uptake.
钙蛋白酶是一种 Ca(2+) 激活的细胞内蛋白酶及其内源性蛋白抑制剂钙蛋白酶抑制剂，在血小板中含量丰富。钙蛋白酶的结构和酶学特性，包括其同工酶和血小板中的钙蛋白酶抑制剂，已经得到了充分的描述。此外，血小板钙蛋白酶已被证明可以切割各种内源性多肽。然而，血小板钙蛋白酶的激活方式和生理功能尚未阐明。我们最近用细胞通透性钙蛋白酶拮抗剂和特异性抗体对血小板钙蛋白酶的研究表明，钙蛋白酶不参与血小板激活的早期阶段，如形态变化和聚集，而是参与血小板激活的后期阶段，如细胞骨架重组和 Ca(2+)摄取。
