Thromboplastin

Literature References: An integral membrane glycoprotein which, in the presence of Ca2+ ions, initiates coagulation by augmenting the proteolytic attack of factor VII on factors IX and X, q.q.v.: Nemerson, Biochemistry 5, 601 (1966). Prepn from cattle brains: Hess, J. Am. Med. Assoc. 66, 558 (1916). From rabbit brains or lung tissue: Singher, Swart, US 2842480 (1958 to Ortho); see also US 2847347 and US 2847350 (1958 to Ortho). Purification of bovine tissue factor: R. Bach et al., J. Biol. Chem. 256, 8324 (1981). The tissue thromboplastin activity seems to be brought about by a lipoprotein comprising a combination of phospholipids: phosphatidyl ethanolamine (PE), phosphatidyl serine (PS), and phosphatidyl choline (PC): R. B. Hunter, et al., Fibrinogen and Fibrin Turnover of Clotting Factors (Schattauer, Stuttgart, 1963) pp 429-454. Removal of phospholipids from tissue factor results in loss of coagulant activity as well as solubilizing the protein component. Purification and characterization of the protein component: Nemerson, Pitlick, Biochemistry 9, 5100 (1970); of tissue factor apoprotein: F. A. Pitlick, Y. Nemerson, Methods Enzymol. 45B, 37-48 (1976). Located on the plasma membrane of endothelial cells readily available for complexing with clotting factors: Zeldis et al., Science 175, 766 (1972). Synthesis by cultured cells: Zacharski, McIntyre, J. Med. 4, 118 (1973). Possibly a vitamin K dependent clotting factor: L. R. Zacharski et al., Ann. N.Y. Acad. Sci. 370, 311 (1981). Use as clinical reagent: F. D. Ziegler et al., Ann. Clin. Lab. Sci. 11, 202 (1981); A. L. Suchman, P. F. Griner, Ann. Intern. Med. 104, 810 (1986).