Mohri H, Ohkubo T
First Department of Internal Medicine, School of Medicine, Yokohama City University, Japan.
Am J Clin Pathol. 1991 Nov;96(5):605-9. doi: 10.1093/ajcp/96.5.605.
Vitronectin, which is present in both plasma and extracellular matrix, inhibits the complement cascade and promotes the growth and attachment of cells in vitro. Like other adhesive proteins such as fibrinogen, von Willebrand factor, and fibronectin, vitronectin contains the sequence Arg-Gly-Asp and binds to some members of the family of receptors called integrins. Platelet membrane glycoprotein IIb-IIIa (GPIIb-IIIa) is well known as a member of integrins that bind to vitronectin as well as to fibrinogen, von Willebrand factor, and fibronectin. The interaction of vitronectin with GPIIb-IIIa was studied. Vitronectin bound to thrombin-stimulated platelets in a calcium-dependent, specific, and saturable manner with a molecular weight of 290 nmol/L and 9,100 sites per platelet. The binding was inhibited by the other adhesive proteins with IC50s of 0.078-0.15 mumol/L. The binding also was inhibited by the tetrapeptide Arg-Gly-Asp-Ser and the monoclonal antibody to GPIIb-IIIa (LJ-CP8). Vitronectin inhibited thrombin-induced platelet aggregation in a dose-dependent manner and fibrinogen enhanced platelet aggregation. These results suggest that vitronectin might modulate platelet aggregates by interfering with the interaction of fibrinogen with thrombin-activated GPIIb-IIIa.
玻连蛋白存在于血浆和细胞外基质中，它能抑制补体级联反应，并在体外促进细胞生长和黏附。与其他黏附蛋白如纤维蛋白原、血管性血友病因子和纤连蛋白一样，玻连蛋白含有精氨酸-甘氨酸-天冬氨酸序列，并能与一类称为整合素的受体家族中的某些成员结合。血小板膜糖蛋白IIb-IIIa（GPIIb-IIIa）是整合素家族的一员，它既能与玻连蛋白结合，也能与纤维蛋白原、血管性血友病因子和纤连蛋白结合，这是众所周知的。研究了玻连蛋白与GPIIb-IIIa的相互作用。玻连蛋白以钙依赖性、特异性和饱和性的方式与凝血酶刺激的血小板结合，分子量为290 nmol/L，每个血小板有9100个结合位点。这种结合受到其他黏附蛋白的抑制，IC50为0.078 - 0.15 μmol/L。这种结合也受到四肽精氨酸-甘氨酸-天冬氨酸-丝氨酸和抗GPIIb-IIIa单克隆抗体（LJ-CP8）的抑制。玻连蛋白以剂量依赖性方式抑制凝血酶诱导的血小板聚集，而纤维蛋白原则增强血小板聚集。这些结果表明，玻连蛋白可能通过干扰纤维蛋白原与凝血酶激活的GPIIb-IIIa之间的相互作用来调节血小板聚集物。
