Tissue factor pathway inhibitor endocytosis

Abstract

Tissue factor pathway inhibitor (TFPI), a 42 kD protein, provides the physiological inhibition of tissue factor initiated coagulation by inhibition of both factor Xa and factor VIIa/tissue factor. In plasma, most TFPI is lipoprotein bound with an additional 'releasable' pool bound to the endothelial cell surface. TFPI clearance is via receptor mediated endocytosis into liver. Heparin sulfate proteoglycans and LRP (low density lipoprotein receptor-related protein), an extremely large (~600 kD) cell surface protein, primarily mediate this clearance, although additional TFPI binding sites and endocytosis pathways exist.