Schollmeyer J V, Rao G H, White J G
Am J Pathol. 1978 Nov;93(2):433-46.
A protein (molecular weight, approximately 250,000) with actin-binding properties has been isolated from human platelets. Addition of the actin-binding protein (ABP) to semiviscous solutions of purified actin containing troponin-tropomyosin (TM-TP) complex resulted in formation of viscous gels consisting of randomly associated actin TM-TP filaments. alpha-Actinin (alphaA), a muscle protein recently detected in platelets, also induced random cross-linking of dissociated actin into gels. Sequential addition of ABP and alphaA resulted in gels consisting of parallel associated actin TM-TP filaments in bundles, suggesting a cooperative interaction. Cytochalasin B (CB) had no apparent effect on the cross-linking of randomly associated actin TM-TP filaments induced by either protein alone but prevented development of bundles of parallel filaments when ABP and alphaA were added sequentially. In addition, CB disrupted the bundles of parallel associated actin TM-TP filaments when added to gels already formed by the dual action of ABP and alphaA and caused simultaneous release of alphaA from the complexes to the supernatant. The findings suggest that platelet ABP and alphaA may induce actin filaments to form the parallel associations observed in platelet pseudopods.
一种具有肌动蛋白结合特性的蛋白质（分子量约为250,000）已从人血小板中分离出来。将肌动蛋白结合蛋白（ABP）添加到含有肌钙蛋白-原肌球蛋白（TM-TP）复合物的纯化肌动蛋白半粘性溶液中，导致形成由随机关联的肌动蛋白TM-TP细丝组成的粘性凝胶。α-辅肌动蛋白（αA）是最近在血小板中检测到的一种肌肉蛋白，它也能诱导解离的肌动蛋白随机交联形成凝胶。依次添加ABP和αA会形成由平行排列成束的肌动蛋白TM-TP细丝组成的凝胶，这表明存在协同相互作用。细胞松弛素B（CB）对单独由任何一种蛋白质诱导的随机关联的肌动蛋白TM-TP细丝的交联没有明显影响，但当依次添加ABP和αA时，它会阻止平行细丝束的形成。此外，当将CB添加到已经由ABP和αA的双重作用形成的凝胶中时，它会破坏平行排列的肌动蛋白TM-TP细丝束，并导致αA同时从复合物中释放到上清液中。这些发现表明，血小板ABP和αA可能诱导肌动蛋白细丝形成在血小板伪足中观察到的平行关联。
