Ware J, Russell S R, Marchese P, Ruggeri Z M
Roon Research Center for Arteriosclerosis and Thrombosis, Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037.
J Biol Chem. 1993 Apr 15;268(11):8376-82.
Platelets are cytoplasmic fragments of megakaryocytes and, therefore, their membrane proteins cannot be manipulated by expression methods in culture. To overcome this limitation, we have expressed human glycoprotein (GP) Ib alpha in transgenic mouse megakaryocytes and found that it was present on the surface of platelets associated with the mouse GP Ib beta subunit. This finding demonstrates that assembly of the heterooligomeric GP Ib complex occurs through mechanisms conserved across species. In contrast, the receptor function of GP Ib exhibited restricted species specificity, since only the chimeric complex containing human GP Ib alpha bound human von Willebrand factor and supported platelet aggregation mediated by ristocetin. These studies demonstrate the transgenic engineering of a platelet adhesion receptor under control of the human GP Ib alpha promoter and illustrate a new approach to manipulate platelet receptors and study structure-function relationships in hemostasis and thrombosis.
血小板是巨核细胞的胞质片段，因此，其膜蛋白无法通过培养中的表达方法进行操控。为克服这一限制，我们在转基因小鼠巨核细胞中表达了人糖蛋白（GP）Ibα，发现它存在于与小鼠GP Ibβ亚基相关的血小板表面。这一发现表明，异源寡聚体GP Ib复合物的组装通过跨物种保守的机制发生。相比之下，GP Ib的受体功能表现出有限的物种特异性，因为只有含人GP Ibα的嵌合复合物能结合人血管性血友病因子并支持瑞斯托菌素介导的血小板聚集。这些研究证明了在人GP Ibα启动子控制下对血小板黏附受体进行转基因工程改造，并阐明了一种操控血小板受体以及研究止血和血栓形成中结构-功能关系的新方法。
