Fukao H, Matsuo O
Department of Physiology, Kinki University School of Medicine.
Nihon Rinsho. 1993 Jun;51(6):1620-6.
Activation of blood fibrinolysis is initiated by the activation of plasminogen to plasmin by plasminogen activator (PA). The plasmin thus produced can degrade fibrin, the main component of thrombus. Tissue-type PA (t-PA) which is mainly secreted from vascular endothelial cells possesses a high affinity for fibrin in contrast to urokinase-type PA (u-PA). Enzymatic activity of t-PA is expressed in either single-chain form or two-chain form. Further, t-PA activity enhanced markedly in the presence of fibrin; 600-1,000-fold increase. Thus, the thrombolytic therapy is now being performed by using t-PA. The mechanism for thrombolysis by t-PA involves the activation of fibrinolytic system on the fibrin surface. The kringle 2 domain of t-PA molecule plays an important role on the binding to fibrin. But in single-chain t-PA, finger domain plays a role for its binding to fibrin. Recent studies have revealed that the t-PA specific receptor (t-PAR) is expressed on the endothelial cells which localizes t-PA activity by fixing t-PA around the cells.
血液纤维蛋白溶解的激活是由纤溶酶原激活剂（PA）将纤溶酶原激活为纤溶酶引发的。由此产生的纤溶酶可降解血栓的主要成分纤维蛋白。与尿激酶型纤溶酶原激活剂（u-PA）相比，主要由血管内皮细胞分泌的组织型纤溶酶原激活剂（t-PA）对纤维蛋白具有高亲和力。t-PA的酶活性以单链形式或双链形式表达。此外，在纤维蛋白存在的情况下，t-PA活性显著增强；增加600 - 1000倍。因此，现在正在使用t-PA进行溶栓治疗。t-PA溶栓的机制涉及纤维蛋白表面纤溶系统的激活。t-PA分子的kringle 2结构域在与纤维蛋白的结合中起重要作用。但在单链t-PA中，指状结构域在其与纤维蛋白的结合中起作用。最近的研究表明，t-PA特异性受体（t-PAR）在内皮细胞上表达，通过将t-PA固定在细胞周围来定位t-PA活性。
