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Thrombin Receptors of Human Platelets: Thrombin Binding and Antithrombin Properties of Glycoprotein I
Author(s) -
Ganguly P.,
Gould N. L.
Publication year - 1979
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1979.tb03706.x
Subject(s) - thrombin , fibrinogen , antithrombin , chemistry , glycoprotein , gel electrophoresis , biochemistry , platelet , clotting time , affinity chromatography , polyacrylamide gel electrophoresis , chromatography , microbiology and biotechnology , biology , immunology , heparin , enzyme
Washed human platelets were solubilized and the proteins were separated by preparative gel electrophoresis in the presence of sodium dodecyl sulphate. The gel was cut into slices and the effect of the eluted proteins on the clotting of fibrinogen by thrombin was evaluated. The isolate from only one gel slice strongly inhibited the clotting of fibrinogen. The prolongation of the clotting time was dependent on the concentration of the protein and reached a plateau around 5 μg. Gel electrophoresis of this isolate showed a prominent glycoprotein with an apparent M r =150 000. Gel filtration studies with [ 125 I]thrombin showed that the protein isolate bound a significant amount of thrombin which could be displaced with unlabelled thrombin. Another preparation from the same gel or purified γ‐globulin did not bind thrombin or prolong the clotting time of fibrinogen. Glycoprotein I was isolated from human platelets by affinity chromatography on lectin–Sepharose columns. The isolated glycoprotein prolonged the clotting of fibrinogen and bound [ 125 I]thrombin which could be displaced by unlabelled thrombin. It is proposed that the high affinity receptor of thrombin on human platelets is glycoprotein I. In addition, the antithrombin activity of intact platelets is due to binding of thrombin to this glycoprotein.