Lahav J, Lawler J, Gimbrone M A
Eur J Biochem. 1984 Nov 15;145(1):151-6. doi: 10.1111/j.1432-1033.1984.tb08534.x.
Thrombospondin synthesized and secreted by human endothelial cells in culture binds specifically to fibronectin immobilized on Sepharose beads. It can also bind to immobilized platelet-derived thrombospondin but not to immobilized gelatin or albumin. These interactions are not dependent on the presence of divalent cations or of other secreted materials. Purified platelet thrombospondin binds to fibronectin and fibrinogen immobilized on plastic surfaces with dissociation constants of 1.12 +/- 0.37 X 10(-7) M and 1.27 +/- 0.41 X 10(-7) M respectively, and to thrombospondin immobilized on plastic with dissociation constant of 4.82 +/- 1.01 X 10(-7) M. The affinities of interaction are not significantly affected by removal of divalent cations. Soluble fibrinogen inhibits binding of thrombospondin to fibronectin regardless of which of the latter two is surface-bound. Thrombospondin-fibronectin interaction is also inhibited by soluble thrombospondin. The binding of soluble thrombospondin to surface-bound fibrinogen is inhibited both by soluble fibronectin and soluble fibrinogen. These results suggest that thrombospondin plays a role both in platelet-platelet aggregation and in platelet-substratum adhesion, and that it may also take part in the construction of the extracellular matrix.
培养的人内皮细胞合成并分泌的血小板反应蛋白能特异性地结合固定在琼脂糖珠上的纤连蛋白。它也能结合固定化的血小板衍生血小板反应蛋白，但不能结合固定化的明胶或白蛋白。这些相互作用不依赖于二价阳离子或其他分泌物质的存在。纯化的血小板血小板反应蛋白以解离常数分别为1.12±0.37×10⁻⁷M和1.27±0.41×10⁻⁷M结合固定在塑料表面的纤连蛋白和纤维蛋白原，并以解离常数4.82±1.01×10⁻⁷M结合固定在塑料上的血小板反应蛋白。去除二价阳离子对相互作用的亲和力没有显著影响。可溶性纤维蛋白原抑制血小板反应蛋白与纤连蛋白的结合，无论后者哪一种是表面结合的。可溶性血小板反应蛋白也抑制血小板反应蛋白-纤连蛋白的相互作用。可溶性血小板反应蛋白与表面结合的纤维蛋白原的结合受到可溶性纤连蛋白和可溶性纤维蛋白原的抑制。这些结果表明，血小板反应蛋白在血小板-血小板聚集和血小板-基质黏附中均起作用，并且它可能也参与细胞外基质的构建。
