Asch A S, Barnwell J, Silverstein R L, Nachman R L
J Clin Invest. 1987 Apr;79(4):1054-61. doi: 10.1172/JCI112918.
Thrombospondin (TSP), a 450-kD multifunctional glycoprotein with a broad tissue distribution, is secreted upon platelet stimulation, binds to the activated platelet surface, and supports platelet aggregation. We have identified and isolated an 88-kd membrane glycoprotein present in platelets, endothelial cells, monocytes, and a variety of human tumor cell lines that is the membrane binding site for TSP. Endogenous platelet TSP binding to thrombin- and ionophore-stimulated human platelets was inhibited in the presence of the monoclonal antibody OKM5. TSP binding to C32 melanoma cells and HT1080 fibrosarcoma cells was specific and also inhibitable with OKM5 Mab. Cell labeling followed by specific immunoprecipitation demonstrated biosynthesis of a single 88-kD glycoprotein. Binding of TSP to the isolated membrane protein was specific and saturable. These studies identify an 88-kD membrane glycoprotein that reacts with the monoclonal antibody, OKM5, and may function as the cellular TSP receptor.
血小板反应蛋白（TSP）是一种分子量为450kD的多功能糖蛋白，广泛分布于组织中，在血小板受到刺激时分泌，与活化的血小板表面结合，并支持血小板聚集。我们已经鉴定并分离出一种存在于血小板、内皮细胞、单核细胞和多种人类肿瘤细胞系中的88kD膜糖蛋白，它是TSP的膜结合位点。在单克隆抗体OKM5存在的情况下，内源性血小板TSP与凝血酶和离子载体刺激的人类血小板的结合受到抑制。TSP与C32黑色素瘤细胞和HT1080纤维肉瘤细胞的结合具有特异性，并且也可被OKM5单克隆抗体抑制。细胞标记后进行特异性免疫沉淀显示生物合成了一种单一的88kD糖蛋白。TSP与分离的膜蛋白的结合具有特异性且可饱和。这些研究鉴定出一种与单克隆抗体OKM5反应的88kD膜糖蛋白，它可能作为细胞TSP受体发挥作用。
