Cellular processing of bovine factors X and Xa by cultured bovine aortic endothelial cells.
Open Access
- 1 August 1985
- journal article
- research article
- Published by Rockefeller University Press in The Journal of Experimental Medicine
- Vol. 162 (2), 559-572
- https://doi.org/10.1084/jem.162.2.559
Abstract
Factor X and Factor Xa bind specifically to distinct sites on the endothelial cell surface. Since the coagulant activity of a cell-bound clotting protein is dependent on its remaining on the cell surface, endocytosis and degradation studies were carried out. Cell-bound factor X was internalized at 0.07 fmol/min/106 cells, a rate slower than its dissociation from the cell surface. Endocytosed Factor X was not degraded, but was returned to the cell surface. Factor Xa was internalized at an initial rate of 0.38 fmol/min/106 cells and subsequently degraded at about the same rate. The degradation of Factor Xa was prevented by chloroquine. Factor Xa is internalized and degraded by a lysosomal-dependent pathway. Studies with Factor X- and Xa-colloidal gold conjugates showed endocytosis proceeding at coated pit regions, and accumulation of Factor Xa-gold particles in lysosome-like stuctures. Endocytosis was studied as a clearance pathway for cell-bound Factor Xa by activating Factor X with Factors IXa and VIII on the endothelial cell surface. Endocytosis of the Factor Xa formed was significant, as only 44% of the Factor Xa formed was released into the supernatant, whereas the remainder was internalized and degraded. Endocytosis of Factor Xa bound to its specific endothelial cell sites may be an important factor in the balance of vessel wall hemostatic mechanisms.Keywords
This publication has 42 references indexed in Scilit:
- Synthesis of fibrinolytic activator and inhibitor by endothelial cellsProceedings of the National Academy of Sciences, 1977
- Alpha 2-macroglobulin and antithrombin-heparin cofactor: modulators of hemostatic and inflammatory reactions. Alpha 2-macroglobulin.1976
- [13] ProthrombinMethods in Enzymology, 1976
- Mechanism of activation of bovine factor X (Stuart factor) by intrinsic and extrinsic pathwaysBiochemistry, 1974
- The Role of Surface Carbohydrates in the Hepatic Recognition and Transport of Circulating GlycoproteinsPublished by Wiley ,1974
- Isolation and characterization of bovine factor IX (Christmas factor)Biochemistry, 1973
- Synthesis of Antihemophilic Factor Antigen by Cultured Human Endothelial CellsJCI Insight, 1973
- The labelling of proteins to high specific radioactivities by conjugation to a 125I-containing acylating agent. Application to the radioimmunoassayBiochemical Journal, 1973
- Methods for the Production of Clinically Effective Intermediate and High-Purity Factor-VIII ConcentratesBritish Journal of Haematology, 1971
- The Reliability of Molecular Weight Determinations by Dodecyl Sulfate-Polyacrylamide Gel ElectrophoresisJournal of Biological Chemistry, 1969