Fox J E
Glastone Institute of Cardiovascular Disease, Department of Pathology, University of California, San Francisco 94140.
Adv Exp Med Biol. 1993;344:175-85. doi: 10.1007/978-1-4615-2994-1_13.
The platelet cytoskeleton contains two actin filament-based components. One is the cytoplasmic actin filaments that fill the cytoplasm and mediate contractile events. The other is the membrane skeleton that coats the plasma membrane and regulates properties of the membrane such as its contours and stability and the lateral distribution of membrane glycoproteins. Recent work reviewed in this article indicates that the GP IIb-IIIa complex can associate with the membrane skeleton. Upon platelet activation, GP IIb-IIIa becomes competent to bind its adhesive ligand, fibrinogen. This induces a reorganization of the cytoskeleton such that the membrane skeletal proteins with which GP IIb-IIIa is associated become associated with underlying cytoplasmic filaments. As in focal contacts of cultured cells, this ligand-induced association of GP IIb-IIIa with cytoplasmic actin filaments regulates the ability of GP IIb-IIIa to bind adhesive ligand. Intracellular enzymes that are activated as a consequence of ligand binding to the GP IIb-IIIa complex include tyrosine kinase(s) and calpain, making these potential candidates for enzymes inducing the two-way signaling across the membrane. Additional candidates include phosphoinositide 3-kinase and protein kinase C, other enzymes that have been detected in focal contacts of aggregating platelets. Future studies identifying interactions between the GP IIb-IIIa complex and membrane skeletal proteins should help to further elucidate the significance of the GP IIb-IIIa in cytoskeleton interaction in regulating integrin-mediated transmembrane signaling in platelets.
血小板细胞骨架包含两个基于肌动蛋白丝的组分。一个是填充细胞质并介导收缩事件的细胞质肌动蛋白丝。另一个是覆盖质膜并调节膜特性（如膜轮廓、稳定性以及膜糖蛋白的侧向分布）的膜骨架。本文所综述的近期研究表明，糖蛋白IIb-IIIa复合物可与膜骨架结合。血小板激活后，糖蛋白IIb-IIIa能够结合其黏附配体纤维蛋白原。这会引发细胞骨架的重组，使得与糖蛋白IIb-IIIa相关联的膜骨架蛋白与下方的细胞质丝相连。如同培养细胞的黏着斑一样，这种由配体诱导的糖蛋白IIb-IIIa与细胞质肌动蛋白丝的结合调节了糖蛋白IIb-IIIa结合黏附配体的能力。因配体与糖蛋白IIb-IIIa复合物结合而被激活的细胞内酶包括酪氨酸激酶和钙蛋白酶，这使得它们成为诱导跨膜双向信号传导的潜在候选酶。其他候选酶包括磷脂酰肌醇3激酶和蛋白激酶C，这些酶也在聚集血小板的黏着斑中被检测到。未来确定糖蛋白IIb-IIIa复合物与膜骨架蛋白之间相互作用的研究，应有助于进一步阐明糖蛋白IIb-IIIa在调节血小板中整合素介导的跨膜信号传导的细胞骨架相互作用中的重要性。
