Saito Y, Imada T, Takagi J, Kikuchi T, Inada Y
J Biol Chem. 1986 Jan 25;261(3):1355-8.
We have studied the binding of collagen fibers with platelet proteins using affinity chromatography on collagen-Sepharose. Only a few proteins from a platelet lysate were trapped by this column. When denatured collagen (gelatin) was used as the affinity ligand, the major protein did not bind and was identified as platelet Factor XIII by polyacrylamide gel electrophoresis, immunoprecipitation, and enzymic activity. This is a zymogen form of transglutaminase, which corresponds to the "a" subunit of the coagulation factor in plasma. Immunoglobulins specific for platelet Factor XIII obtained from antiserum raised against plasma Factor XIII were able to initiate platelet aggregation by themselves, in strong contrast to nonspecific antibodies. This specific immunoglobulin-mediated platelet aggregation required the presence of Ca2+. It was inhibited by aspirin and prostacyclin, but not by specific inhibitors for other agonists. These data suggest the possibility that the zymogen form of Factor XIII is located on the surface of platelets and may play a key role as the receptor for collagen-induced platelet aggregation.
我们利用胶原-琼脂糖亲和层析研究了胶原纤维与血小板蛋白的结合情况。血小板裂解液中只有少数几种蛋白质能被该柱捕获。当使用变性胶原（明胶）作为亲和配体时，主要蛋白质不结合，通过聚丙烯酰胺凝胶电泳、免疫沉淀和酶活性鉴定为血小板因子 XIII。这是转谷氨酰胺酶的一种酶原形式，对应于血浆中凝血因子的“a”亚基。从针对血浆因子 XIII 产生的抗血清中获得的针对血小板因子 XIII 的特异性免疫球蛋白能够自行引发血小板聚集，这与非特异性抗体形成强烈对比。这种特异性免疫球蛋白介导的血小板聚集需要 Ca2+ 的存在。它受到阿司匹林和前列环素的抑制，但不受其他激动剂的特异性抑制剂的抑制。这些数据表明，因子 XIII 的酶原形式可能位于血小板表面，并可能作为胶原诱导的血小板聚集的受体发挥关键作用。
