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Covalent binding of human thrombin to a human endothelial cell-associated protein

Journal Article · · Experimental Cell Research; (United States)

Binding of {sup 125}I-thrombin to endothelial cells derived from human umbilical vein was studied in tissue culture. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography revealed covalent binding of thrombin in a 72-kDa complex. Some characteristics of the 72-kDa complex were compared to those of the complexes formed between thrombin and protease nexin originating from fibroblasts or platelets: (1) its electrophoretic mobility on SDS-PAGE is identical to that of the thrombin-platelet protease nexin complex, (2) heparin prevents the appearance of the complex on the cell surface, (3) plasmin in a 100-fold molar excess prevents the covalent linkage of thrombin, suggesting that the protease specificity of the endothelial component involved in the complex might not be restricted to thrombin. Yet no release, nor any secretion of the endothelial protein, could be detected. These results indicate that active thrombin binds covalently to a specific endothelial protein that is in several respects similar to fibroblasts or platelet protease nexin and provides a thrombin binding site distinct from thrombomodulin and glycosaminoglycans.

OSTI ID:
5623323
Journal Information:
Experimental Cell Research; (United States), Journal Name: Experimental Cell Research; (United States) Vol. 181:1; ISSN ECREA; ISSN 0014-4827
Country of Publication:
United States
Language:
English