Interaction of thrombin with endothelial cells in the presence of fibrinogen and alpha 2-macroglobulin.
Binding of thrombin to cultured endothelial cells has been studied in the presence of fibrinogen and alpha 2-macroglobulin. Both fibrinogen and alpha 2-macroglobulin inhibit the interaction of thrombin with endothelial cells. Whereas fibrinogen decreases the rate of activation by the thrombin-thrombomodulin complex of protein C, thrombomodulin inhibits the rate of inactivation by alpha 2-macroglobulin thrombin. alpha 2-macroglobulin also binds to endothelial cells; (Kd = 3 x 10(-7) M with 3 x 10(5) binding sites/cell), and the rate of binding of the alpha 2-macroglobulin to endothelial cells is faster than its complex formation with the thrombin. The data suggest that essentially the cell-bound form of fibrinogen and alpha 2-macroglobulin influences thrombin binding and functions.
Léránt
I
I
2nd Institute of Biochemistry, Semmelweis University Medical School, Budapest, Hungary.
Kovács
T
T
Papp
B
B
Mandl
J
J
Lambin
P
P
Machovich
R
R
D001011:Aorta; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000502:physiology; D005340:Fibrinogen / Q000737:chemistry* / Q000502:physiology; D006801:Humans; D011956:Receptors, Cell Surface / Q000737:chemistry*; D018179:Receptors, Thrombin; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000737:chemistry; D000511:alpha-Macroglobulins / Q000737:chemistry* / Q000502:physiology
D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D000511:alpha-Macroglobulins; D005340:Fibrinogen; D013917:Thrombin