ROLE OF CELL-SURFACE LYSINES IN PLASMINOGEN BINDING TO CELLS - IDENTIFICATION OF ALPHA-ENOLASE AS A CANDIDATE PLASMINOGEN RECEPTOR
ROLE OF CELL-SURFACE LYSINES IN PLASMINOGEN BINDING TO CELLS - IDENTIFICATION OF ALPHA-ENOLASE AS A CANDIDATE PLASMINOGEN RECEPTOR
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DOI：
10.1021/bi00220a034
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发表时间：
1991-02-12
期刊：
影响因子：
2.9
通讯作者：
PLOW, EF
中科院分区：
文献类型：
--
作者：
MILES, LA;DAHLBERG, CM;PLOW, EF
纤溶酶原与细胞表面结合导致纤溶酶原活化增强、纤溶酶蛋白水解活性在细胞表面的定位以及保护纤溶酶免受α-2-抗纤溶酶的影响。我们试图使用 U937 单核细胞作为模型来表征有核细胞上的候选纤溶酶原结合位点，特别关注具有适当放置的赖氨酸残基的细胞表面蛋白作为候选纤溶酶原受体的作用。具有游离α-羧基的赖氨酸衍生物和具有羧基末端赖氨酰残基的肽是纤溶酶原与细胞结合的有效抑制剂。其中一种肽代表 α-2-抗纤溶酶的羧基端 19 个氨基酸，其效果比其他带有羧基端赖氨酸的肽大约高 5 倍。因此，除了羧基末端赖氨酰残基之外，细胞表面蛋白的其他结构特征也可能影响它们对纤溶酶原的亲和力。亲和层析已用于从 U937 细胞中分离候选纤溶酶原受体。回收了 M(r) 54 000 的主要蛋白质，并通过免疫化学和功能标准鉴定为 α-烯醇酶。 α-烯醇酶存在于细胞表面，并且能够在配体印迹分析中结合纤溶酶原。与α-烯醇酶分子量相似的纤溶酶原结合活性也存在于多种其他细胞类型中。 α-烯醇酶的羧肽酶 B 处理消除了其结合纤溶酶原的能力，这与 C 末端赖氨酰残基的存在一致。因此，具有羧基末端赖氨酰残基的细胞表面蛋白似乎起到纤溶酶原结合位点的作用，并且α-烯醇酶已被确定为此类受体的突出代表。
Plasminogen binding to cell surfaces results in enhanced plasminogen activation, localization of the proteolytic activity of plasmin on cell surfaces, and protection of plasmin from alpha-2-antiplasmin. We sought to characterize candidate plasminogen binding sites on nucleated cells, using the U937 monocytoid cell as a model, specifically focusing on the role of cell-surface proteins with appropriately placed lysine residues as candidate plasminogen receptors. Lysine derivatives with free alpha-carboxyl groups and peptides with carboxy-terminal lysyl residues were effective inhibitors of plasminogen binding to the cells. One of the peptides, representing the carboxy-terminal 19 amino acids of alpha-2-antiplasmin, was approximately 5-fold more effective than other with carboxy-terminal lysines. Thus, in addition to a carboxy-terminal lysyl residue, other structural features of the cell-surface proteins may influence their affinity for plasminogen. Affinity chromatography has been used to isolate candidate plasminogen receptors from U937 cells. A major protein of M(r) 54 000 was recovered and identified as alpha-enolase by immunochemical and functional criteria. alpha-Enolase was present on the cell surface and was capable of binding plasminogen in ligand blotting analyses. Plasminogen binding activity of a molecular weight similar to alpha-enolase also was present in a variety of other cell types. Carboxypeptidase B treatment of alpha-enolase abolished its ability to bind plasminogen, consistent with the presence of a C-terminal lysyl residue. Thus, cell-surface proteins with carboxy-terminal lysyl residues appear to function as plasminogen binding sites, and alpha-enolase has been identified as a prominent representative of this class of receptors.