Dudani A K, Hashemi S, Aye M T, Ganz P R
Ottawa Blood Centre, Canadian Red Cross Society, Ontario.
Mol Cell Biochem. 1991 Dec 11;108(2):133-9. doi: 10.1007/BF00233117.
To identify and characterize endothelial cell surface components that bind plasminogen, we used ligand-blotting to study binding of plasminogen to sodium dodecyl sulphate solubilized extracts of human umbilical vein endothelial cells. It was observed that glu-plasminogen bound predominantly to a 45 kDa endothelial cell polypeptide. The interaction of labelled glu-plasminogen with this polypeptide was reversible and specific as the binding could be inhibited by both excess cold lysine and unlabelled glu-plasminogen but not by unrelated proteins. Binding of glu-plasminogen to cell extracts prepared from endothelial cells that had been pretreated with proteinase K was significantly reduced indicating that the 45 kDa polypeptide is a cell-surface protein. The cell-surface localization of the 45 kDa polypeptide was also indicated by the positive interaction of glu-plasminogen with membrane fractions of endothelial cells. Lys-plasminogen also interacted with the 45 kDa polypeptide in a specific manner and reversibility experiments indicated that lys-plasminogen could also displace the bound glu-plasminogen. Since binding of plasminogen to the 45 kDa endothelial cell surface polypeptide was very similar to plasminogen binding to intact endothelial cells, we propose that the 45 kDa protein represents one of the major receptors for plasminogen on human endothelial cells.
为了鉴定和表征结合纤溶酶原的内皮细胞表面成分，我们使用配体印迹法研究纤溶酶原与人脐静脉内皮细胞十二烷基硫酸钠溶解提取物的结合。观察到谷氨酸纤溶酶原主要结合到一种45 kDa的内皮细胞多肽上。标记的谷氨酸纤溶酶原与该多肽的相互作用是可逆且特异的，因为过量的冷赖氨酸和未标记的谷氨酸纤溶酶原均可抑制结合，但无关蛋白则不能。谷氨酸纤溶酶原与经蛋白酶K预处理的内皮细胞制备的细胞提取物的结合显著减少，表明该45 kDa多肽是一种细胞表面蛋白。谷氨酸纤溶酶原与内皮细胞膜组分的阳性相互作用也表明了该45 kDa多肽的细胞表面定位。赖氨酸纤溶酶原也以特异方式与该45 kDa多肽相互作用，可逆性实验表明赖氨酸纤溶酶原也能取代结合的谷氨酸纤溶酶原。由于纤溶酶原与45 kDa内皮细胞表面多肽的结合与纤溶酶原与完整内皮细胞的结合非常相似，我们认为该45 kDa蛋白代表了人内皮细胞上纤溶酶原的主要受体之一。
