Zafar R S, Walz D A
Department of Physiology, Wayne State University, Detroit, Michigan 48201.
Thromb Res. 1989 Jan 1;53(1):31-44. doi: 10.1016/0049-3848(89)90113-8.
Human platelets contain a single membrane glycoprotein which is susceptible to thrombin proteolysis, glycoprotein V. We have purified 1 mg of glycoprotein V from 10(13) platelets using a combination of gel filtration, hydroxylapatite and ion-exchange chromatographies. Glycoprotein V has a blocked amino-terminus. Following proteolysis by human alpha-thrombin, a major fragment, termed glycoprotein Vf1, had the sequence Gly-Pro-Phe-X-Arg-Pro-Ala-Ala-Asp-Glu-Ser-Val-Glu-Ala-Pro-Val-Asn-Gln-Al a-Glu- Ala-Pro-. The purified glycoprotein was not a substrate for human gamma-thrombin. Glycoprotein V contained 17.5% carbohydrate, with the majority of the carbohydrate consisting of neutral hexoses. Deglycosylated glycoprotein V had a molecular weight of 57.5 kDa compared to the glycosylated protein's 82 kDa and the deglycosylated protein was recognized by polyclonal antibodies raised against glycoprotein V. Immunoelectrophoresis of human and rat platelets and megakaryocytes gave a single immunoreactive band, with the rat glycoprotein having a slightly larger molecular mass. Glycoprotein V is most likely an integral membrane protein.
人血小板含有一种易受凝血酶蛋白水解作用影响的单一膜糖蛋白，即糖蛋白V。我们通过凝胶过滤、羟基磷灰石和离子交换色谱相结合的方法，从10¹³个血小板中纯化出了1毫克糖蛋白V。糖蛋白V的氨基末端被封闭。经人α凝血酶蛋白水解后，一个主要片段，称为糖蛋白Vf1，其序列为甘氨酸-脯氨酸-苯丙氨酸-X-精氨酸-脯氨酸-丙氨酸-丙氨酸-天冬氨酸-谷氨酸-丝氨酸-缬氨酸-谷氨酸-丙氨酸-脯氨酸-缬氨酸-天冬酰胺-谷氨酰胺-丙氨酸-谷氨酸-丙氨酸-脯氨酸-。纯化后的糖蛋白不是人γ凝血酶的底物。糖蛋白V含有17.5%的碳水化合物，其中大部分碳水化合物由中性己糖组成。去糖基化的糖蛋白V分子量为57.5 kDa，而糖基化蛋白的分子量为82 kDa，去糖基化蛋白能被针对糖蛋白V产生的多克隆抗体识别。人和大鼠血小板及巨核细胞的免疫电泳显示出一条单一的免疫反应带，大鼠糖蛋白的分子量略大。糖蛋白V很可能是一种整合膜蛋白。
