van Zonneveld A J, Veerman H, Pannekoek H
J Biol Chem. 1986 Oct 25;261(30):14214-8.
The binding of tissue-type plasminogen activator (t-PA) to fibrin is mediated both by its finger domain and by its kringle-2 domain. In this report, we investigate the relative affinities of these domains for lysine. Human recombinant t-PA deletion-mutant proteins were prepared and their ability to bind to lysine-Sepharose was investigated. Mutants containing the kringle-2 domain bound to lysine-Sepharose, whereas mutants lacking this domain but containing the finger domain, the epidermal growth factor domain or the kringle-1 domain did not bind to lysine-Sepharose. Mutant proteins containing the kringle-2 domain could be specifically eluted from lysine-Sepharose with epsilon-amino caproic acid. This lysine derivative also abolished fibrin binding by the kringle-2 domain but had no effect on the fibrin-binding property of the finger domain. Thus, a lysine-binding site is involved in the interaction of the kringle-2 domain with fibrin but not in the interaction of the finger domain with fibrin. The implications of the nature of these two distinct interactions of t-PA with fibrin on plasminogen activation by t-PA will be discussed.
组织型纤溶酶原激活剂（t-PA）与纤维蛋白的结合是由其指状结构域和kringle-2结构域介导的。在本报告中，我们研究了这些结构域与赖氨酸的相对亲和力。制备了人重组t-PA缺失突变蛋白，并研究了它们与赖氨酸-琼脂糖的结合能力。含有kringle-2结构域的突变体与赖氨酸-琼脂糖结合，而缺乏该结构域但含有指状结构域、表皮生长因子结构域或kringle-1结构域的突变体则不与赖氨酸-琼脂糖结合。含有kringle-2结构域的突变蛋白可用ε-氨基己酸从赖氨酸-琼脂糖上特异性洗脱。这种赖氨酸衍生物也消除了kringle-2结构域与纤维蛋白的结合，但对指状结构域与纤维蛋白的结合特性没有影响。因此，赖氨酸结合位点参与了kringle-2结构域与纤维蛋白的相互作用，而不参与指状结构域与纤维蛋白的相互作用。将讨论t-PA与纤维蛋白这两种不同相互作用的性质对t-PA激活纤溶酶原的影响。
