Hartwig J H, DeSisto M
Department of Medicine, Massachusetts General Hospital.
J Cell Biol. 1991 Feb;112(3):407-25. doi: 10.1083/jcb.112.3.407.
We used high-resolution EM and immunocytochemistry in combination with different specimen preparation techniques to resolve the ultrastructure of the resting platelet cytoskeleton. The periphery of the cytoskeleton, an electron-dense subplasmalemmal region in thin section electron micrographs, is a tightly woven planar sheet composed of a spectrin-rich network whose interstices contain GPIb/IX-actin-binding protein (ABP) complexes. This membrane skeleton connects to a system of curved actin filaments (F-actin) that emanate from a central oval core of F-actin cross-linked by ABP. The predominant interaction of the radial actin filaments with the membrane skeleton is along their sides, and the strongest connection between the membrane skeleton and F-actin is via ABP-GPIb ligands, although there is evidence for spectrin attaching to the ends of the radial actin filaments as well. Since a mechanical separation of the F-actin cores and radial F-actin-GPIb-ABP complexes from the underlying spectrin-rich skeleton leads to the latter's expansion, it follows that the spectrin-based skeleton of the resting cell may be held in a compressed form by interdigitating GPIb/IX complexes which are immobilized by radial F-actin-ABP anchors.
我们结合不同的标本制备技术，使用高分辨率电子显微镜和免疫细胞化学方法来解析静息血小板细胞骨架的超微结构。在超薄切片电子显微照片中，细胞骨架的周边是一个电子致密的亚膜区，是由富含血影蛋白的网络组成的紧密编织的平面薄片，其间隙包含糖蛋白Ib/IX-肌动蛋白结合蛋白（ABP）复合物。这种膜骨架连接到一个弯曲的肌动蛋白丝（F-肌动蛋白）系统，该系统从由ABP交联的F-肌动蛋白的中央椭圆形核心发出。径向肌动蛋白丝与膜骨架的主要相互作用沿着它们的侧面，并且膜骨架与F-肌动蛋白之间最强的连接是通过ABP-糖蛋白Ib配体，尽管也有证据表明血影蛋白也附着在径向肌动蛋白丝的末端。由于从下面富含血影蛋白的骨架机械分离F-肌动蛋白核心和径向F-肌动蛋白-糖蛋白Ib-ABP复合物会导致后者膨胀，因此可以推断，静息细胞基于血影蛋白的骨架可能通过由径向F-肌动蛋白-ABP锚固定的相互交错的糖蛋白Ib/IX复合物以压缩形式保持。
