A sulfated rabbit endothelial cell glycoprotein that inhibits factor VIIa/tissue factor is functionally and immunologically identical to rabbit extrinsic pathway inhibitor (EPI).
Colburn and Buonassisi (In Vitro Cell Dev. Biol. 24, 1133-1136, 1988) have isolated a single chain sulfated glycoprotein inhibitor of factor VIIa/tissue factor-catalyzed activation of factor X from conditioned media of an established rabbit endothelial cell line. We report herein that their endothelial cell-derived inhibitor and extrinsic pathway inhibitor (EPI) isolated from rabbit plasma have identical functional properties with respect to their interactions with factor Xa and with factor VIIa/tissue factor. In addition, the endothelial cell inhibitor and rabbit plasma EPI migrate with the same apparent molecular weights on non-reduced SDS-PAGE and contain similar amounts of N-linked carbohydrate. Like the endothelial cell inhibitor the EPI of rabbit plasma exists as a single chain molecule. Furthermore, the endothelial cell inhibitor is recognized and neutralized by a polyclonal antibody raised against rabbit plasma EPI. We therefore conclude that cultured rabbit endothelial cells produce an inhibitor of factor VIIa/tissue factor activity that is functionally and immunologically identical to rabbit plasma EPI.
Warn-Cramer
B J
BJ
Department of Medicine, University of California, San Diego, La Jolla 92093.
Maki
S L
SL
Rapaport
S I
SI
D000818:Animals; D001120:Arginine; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000502:physiology*; D005167:Factor VII / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000502:physiology; D015942:Factor VIIa / Q000037:antagonists & inhibitors*; D015951:Factor Xa / Q000378:metabolism; D006023:Glycoproteins / Q000276:immunology / Q000502:physiology*; D007106:Immune Sera; D066298:In Vitro Techniques; D008074:Lipoproteins / Q000276:immunology / Q000502:physiology*; D011485:Protein Binding; D011817:Rabbits; D013925:Thromboplastin / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000502:physiology
D006023:Glycoproteins; D007106:Immune Sera; D008074:Lipoproteins; C051928:lipoprotein-associated coagulation inhibitor; D005167:Factor VII; D013925:Thromboplastin; D001120:Arginine; D015942:Factor VIIa; D015951:Factor Xa