VITRONECTIN EXISTS IN 2 STRUCTURALLY AND FUNCTIONALLY DISTINCT FORMS IN HUMAN-PLASMA
VITRONECTIN EXISTS IN 2 STRUCTURALLY AND FUNCTIONALLY DISTINCT FORMS IN HUMAN-PLASMA
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DOI：
10.1016/s0304-4165(89)80019-4
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发表时间：
1989-02-24
期刊：
影响因子：
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通讯作者：
HAYASHI, M
中科院分区：
文献类型：
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作者：
IZUMI, M;YAMADA, KM;HAYASHI, M
玻连蛋白（血清扩散因子、S 蛋白或 Epibolin）是一种血浆糖蛋白，参与细胞粘附以及补体介导的细胞溶解和抗凝血酶 III 功能的调节。玻连蛋白被发现以异质混合物形式存在于新鲜人血浆中，其中 2% 为肝素结合形式，其余为非结合形式。肝素结合玻连蛋白由 6.5 S 聚集体组成，斯托克斯半径为 5.6 nm，富含 65 kDa 多肽，分子含量高，具有推定的未折叠构象。相比之下，非肝素结合玻连蛋白是一种 4.2 S 单体，斯托克斯半径为 3.9 nm，它似乎处于折叠构象，具有免疫学上的隐秘位点。两种玻连蛋白在介导 BHK 成纤维细胞在基质上的扩散方面表现出相似的活性。在血液凝固过程中，5%以上的非肝素结合玻连蛋白转化为肝素结合形式，使该物种的数量增加了3.5倍以上。我们的结果表明，玻连蛋白通常以至少两种结构和功能不同的形式存在于循环血液中，这两种形式可能具有不同的功能。
Vitronectin (serum spreading factor, S-protein or epibolin) is a plasma glycoprotein implicated in cell adhesion, as well as in the regulation of complement-mediated cytolysis and antithrombin III function. Vitronectin was found to exist in fresh human plasma as a heterogeneous mixture consisting of 2% heparin-binding form and the remainder as a non-binding species. Heparin-binding vitronectin consisted of 6.5 S aggregates with a Stokes radius of 5.6 nm, which was enriched in the 65 kDa polypeptide, with a high content of molecules and a putative unfolded conformation. In contrast, non-heparin-binding vitronectin was a 4.2 S monomer with a Stokes radius of 3.9 nm, which appeared to be in a folded conformation with an immunologically cryptic site. Both vitronectins displayed similar activities in mediating the spreading of BHK fibroblastic cells on substrates. During blood coagulation, 5% more of the non-heparin-binding vitronectin was converted into the heparin-binding form, producing a greater than 3.5-fold increase in this species. Our results indicate that vitronectin normally exists in circulating blood in at least two structurally and functionally distinct forms which may serve different functions.