Lasne D, Rendu F, Aiach M
Laboratoire d'hémostase, hôpital Broussais, Paris, France.
Ann Biol Clin (Paris). 1994;52(4):257-60.
Thrombin is a serine protease able to evoke biological responses from a variety of cells, including platelets, endothelial cells, fibroblasts and smooth muscle cells. The structure of the thrombin receptor present in the human megakaryoblastic cell line and in hamster fibroblasts has recently been deduced by expression in the Xenopus laevis oocyte. The cloned receptor is a new member of the seven transmembrane domain receptor family that interacts with G proteins. A large amino-terminal extracellular extension has a cleavage site for thrombin (Leu Asp Pro Arg/Ser Phe Leu Leu,/representing the cleavage site). Thrombin cleaves at this site, unmasking a new amino terminus, that functions like a ligand, binding to an as yet undefined site and eliciting receptor activation. Peptides similar to a new amino terminus created after cleavage are able to mimic thrombin cellular effects. These agonist peptides are used to analyse the role of the cloned receptor in the thrombin-specific response.
凝血酶是一种丝氨酸蛋白酶，能够引发包括血小板、内皮细胞、成纤维细胞和平滑肌细胞在内的多种细胞的生物学反应。最近，通过在非洲爪蟾卵母细胞中表达，推断出了人巨核母细胞系和仓鼠成纤维细胞中存在的凝血酶受体的结构。克隆的受体是与G蛋白相互作用的七跨膜结构域受体家族的新成员。一个大的氨基末端细胞外延伸部分有一个凝血酶切割位点（亮氨酸-天冬氨酸-脯氨酸-精氨酸/丝氨酸-苯丙氨酸-亮氨酸-亮氨酸，/代表切割位点）。凝血酶在此位点切割，暴露出一个新的氨基末端，其功能类似于配体，与一个尚未明确的位点结合并引发受体激活。与切割后产生的新氨基末端相似的肽能够模拟凝血酶的细胞效应。这些激动剂肽用于分析克隆受体在凝血酶特异性反应中的作用。
