Burtin P, Fondaneche M C
Laboratoire d'Immunochimie, Centre National de la Recherche Scientifique, Villejuif, France.
J Natl Cancer Inst. 1988 Jul 20;80(10):762-5. doi: 10.1093/jnci/80.10.762.
We have shown that cells from human tumor cell line SW 1116 have receptors for plasmin and plasminogen. These receptors are the same for the proenzyme and the enzyme, but they have a much higher affinity for plasmin (Kd = 6 X 10(-8) M) than for plasminogen (Kd = 5 X 10(-6) M). Plasminogen binding was strongly increased by preincubation of the tumor cells with urokinase and was inhibited by anti-urokinase serum. Because free plasmin is rapidly neutralized in vivo, it is likely that, under physiological conditions, plasminogen is bound by tumor cells and partially transformed into plasmin by urokinase already present at the surface of these cells. Bound plasmin retains its enzymatic activity, which demonstrates that its binding does not involve the enzyme's active site.
我们已经证明，来自人肿瘤细胞系SW 1116的细胞具有纤溶酶和纤溶酶原的受体。这些受体对酶原和酶是相同的，但它们对纤溶酶（Kd = 6×10⁻⁸ M）的亲和力比对纤溶酶原（Kd = 5×10⁻⁶ M）高得多。用尿激酶预孵育肿瘤细胞可强烈增加纤溶酶原的结合，并被抗尿激酶血清抑制。由于游离纤溶酶在体内会迅速被中和，因此在生理条件下，纤溶酶原很可能被肿瘤细胞结合，并被这些细胞表面已经存在的尿激酶部分转化为纤溶酶。结合的纤溶酶保留其酶活性，这表明其结合不涉及酶的活性位点。
