Piotrowicz R S, Orchekowski R P, Nugent D J, Yamada K Y, Kunicki T J
Blood Center of Southeastern Wisconsin, Milwaukee 53233.
J Cell Biol. 1988 Apr;106(4):1359-64. doi: 10.1083/jcb.106.4.1359.
Soluble fibronectin binds specifically to glycoprotein (GP) IIb-IIIa on thrombin-activated platelets, and this binding is not observed with platelets of patients with Glanzmann's thrombasthenia (GT) which lack GPIIb-IIIa. Here we report that GT platelets retain the ability to interact with fibronectin-coated surfaces. Adhesion to fibronectin does not require platelet activation and is inhibited by soluble fibronectin, antibodies specific for fibronectin, peptides containing the sequence Arg-Gly-Asp and polyclonal antibodies specific for band 3 of the chicken embryo fibroblast fibronectin receptor (anti-band 3). Using anti-band 3, we have purified a second fibronectin receptor from human platelets, a heterodimer composed of glycoproteins previously designated GPIc and GPIIa. The GPIc-IIa complex is found on both GT and normal platelets and appears to be identical to the GP138 kD-GP160 kD complex recently immunopurified by Giancotti et al. (1986. Exp. Cell Res. 163:47-62) and by Sonnenberg et al. (1987. J. Biol. Chem. 268:10376-10383). In this report, we provide the first evidence that GPIc-IIa actually mediates adhesion of platelets to fibronectin-coated surfaces. GPIc-IIa thus represents a second functional fibronectin receptor, distinct from GPIIb-IIIa, that is largely responsible for the adhesion of nonactivated platelets to fibronectin-coated surfaces.
可溶性纤维连接蛋白特异性结合凝血酶激活血小板上的糖蛋白（GP）IIb-IIIa，而在缺乏GPIIb-IIIa的血小板无力症（GT）患者的血小板中未观察到这种结合。在此我们报告，GT血小板保留了与纤维连接蛋白包被表面相互作用的能力。与纤维连接蛋白的黏附不需要血小板激活，且可被可溶性纤维连接蛋白、纤维连接蛋白特异性抗体、含精氨酸-甘氨酸-天冬氨酸序列的肽以及鸡胚成纤维细胞纤维连接蛋白受体带3特异性多克隆抗体（抗带3）所抑制。利用抗带3，我们从人血小板中纯化出了第二种纤维连接蛋白受体，它是一种异二聚体，由先前命名为GPIc和GPIIa的糖蛋白组成。GPIc-IIa复合物存在于GT血小板和正常血小板中，且似乎与最近由詹科蒂等人（1986年。《实验细胞研究》163:47 - 62）以及索南伯格等人（1987年。《生物化学杂志》268:10376 - 10383）免疫纯化得到的GP138 kD - GP160 kD复合物相同。在本报告中，我们首次提供证据表明GPIc-IIa实际上介导血小板与纤维连接蛋白包被表面的黏附。因此，GPIc-IIa代表了第二种功能性纤维连接蛋白受体，不同于GPIIb-IIIa，它在很大程度上负责未激活血小板与纤维连接蛋白包被表面的黏附。
