CRYSTAL STRUCTURE OF THE C2 DOMAIN OF HUMAN COAGULATION FACTOR V: DIMERIC CRYSTAL FORM
[FA5_HUMAN] Defects in F5 are the cause of factor V deficiency (FA5D) [MIM:227400]; also known as Owren parahemophilia. It is a hemorrhagic diastesis.  Defects in F5 are the cause of thrombophilia due to activated protein C resistance (THPH2) [MIM:188055]. THPH2 is a hemostatic disorder due to defective degradation of factor Va by activated protein C. It is characterized by a poor anticoagulant response to activated protein C resulting in tendency to thrombosis.     Defects in F5 are a cause of susceptibility to Budd-Chiari syndrome (BDCHS) [MIM:600880]. A syndrome caused by obstruction of hepatic venous outflow involving either the hepatic veins or the terminal segment of the inferior vena cava. Obstructions are generally caused by thrombosis and lead to hepatic congestion and ischemic necrosis. Clinical manifestations observed in the majority of patients include hepatomegaly, right upper quadrant pain and abdominal ascites. Budd-Chiari syndrome is associated with a combination of disease states including primary myeloproliferative syndromes and thrombophilia due to factor V Leiden, protein C deficiency and antithrombin III deficiency. Budd-Chiari syndrome is a rare but typical complication in patients with polycythemia vera. Defects in F5 may be a cause of susceptibility to ischemic stroke (ISCHSTR) [MIM:601367]; also known as cerebrovascular accident or cerebral infarction. A stroke is an acute neurologic event leading to death of neural tissue of the brain and resulting in loss of motor, sensory and/or cognitive function. Ischemic strokes, resulting from vascular occlusion, is considered to be a highly complex disease consisting of a group of heterogeneous disorders with multiple genetic and environmental risk factors. Defects in F5 are associated with susceptibility to pregnancy loss, recurrent, type 1 (RPRGL1) [MIM:614389]. RPRGL1 is a common complication of pregnancy, resulting in spontaneous abortion before the fetus has reached viability. The term includes all miscarriages from the time of conception until 24 weeks of gestation. Recurrent pregnancy loss is defined as 3 or more consecutive spontaneous abortions.
[FA5_HUMAN] Central regulator of hemostasis. It serves as a critical cofactor for the prothrombinase activity of factor Xa that results in the activation of prothrombin to thrombin.
Publication Abstract from PubMed
Rapid and controlled clot formation is achieved through sequential activation of circulating serine proteinase precursors on phosphatidylserine-rich procoagulant membranes of activated platelets and endothelial cells. The homologous complexes Xase and prothrombinase, each consisting of an active proteinase and a non-enzymatic cofactor, perform critical steps within this coagulation cascade. The activated cofactors VIIIa and Va, highly specific for their cognate proteinases, are each derived from precursors with the same A1-A2-B-A3-C1-C2 architecture. Membrane binding is mediated by the C2 domains of both cofactors. Here we report two crystal structures of the C2 domain of human factor Va. The conserved beta-barrel framework provides a scaffold for three protruding loops, one of which adopts markedly different conformations in the two crystal forms. We propose a mechanism of calcium-independent, stereospecific binding of factors Va and VIIIa to phospholipid membranes, on the basis of (1) immersion of hydrophobic residues at the apices of these loops in the apolar membrane core; (2) specific interactions with phosphatidylserine head groups in the groove enclosed by these loops; and (3) favourable electrostatic contacts of basic side chains with negatively charged membrane phosphate groups.
Crystal structures of the membrane-binding C2 domain of human coagulation factor V.,Macedo-Ribeiro S, Bode W, Huber R, Quinn-Allen MA, Kim SW, Ortel TL, Bourenkov GP, Bartunik HD, Stubbs MT, Kane WH, Fuentes-Prior P Nature. 1999 Nov 25;402(6760):434-9. PMID:10586886
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.