3p70
Structural basis of thrombin-mediated factor V activation: essential role of the hirudin-like sequence Glu666-Glu672 for processing at the heavy chain-B domain junctionStructural basis of thrombin-mediated factor V activation: essential role of the hirudin-like sequence Glu666-Glu672 for processing at the heavy chain-B domain junction
Structural highlights
Disease[THRB_HUMAN] Defects in F2 are the cause of factor II deficiency (FA2D) [MIM:613679]. It is a very rare blood coagulation disorder characterized by mucocutaneous bleeding symptoms. The severity of the bleeding manifestations correlates with blood factor II levels.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Genetic variations in F2 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.[13] Defects in F2 are the cause of thrombophilia due to thrombin defect (THPH1) [MIM:188050]. It is a multifactorial disorder of hemostasis characterized by abnormal platelet aggregation in response to various agents and recurrent thrombi formation. Note=A common genetic variation in the 3-prime untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increased risk of venous thrombosis. Defects in F2 are associated with susceptibility to pregnancy loss, recurrent, type 2 (RPRGL2) [MIM:614390]. 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.[14] [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.[15] [16] 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.[17] [18] [19] [20] [21] 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.[22] 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.[23] Function[THRB_HUMAN] Thrombin, which cleaves bonds after Arg and Lys, converts fibrinogen to fibrin and activates factors V, VII, VIII, XIII, and, in complex with thrombomodulin, protein C. Functions in blood homeostasis, inflammation and wound healing.[24] [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 PubMedThrombin-catalyzed activation of coagulation factor V (FV) is an essential positive feedback reaction within the blood clotting system. Efficient processing at the amino- (Arg(709)-Ser(710)) and carboxy-terminal activation cleavage sites (Arg(1545)-Ser(1546)) requires initial substrate interactions with two clusters of positively charged residues on the proteinase surface, exosites I and II. We addressed the mechanism of activation of human FV using peptides that cover the entire acidic regions preceding these cleavage sites, FV(657-709) (FVa2) and FV(1481-1545) (FVa3). FVa2 appears to interact mostly with exosite I, while both exosites are involved in interactions with the carboxy-terminal linker. The 1.7-A crystal structure of irreversibly inhibited thrombin bound to FVa2 unambiguously reveals docking of FV residues Glu(666)-Glu(672) to exosite I. These findings were confirmed in a second, medium-resolution structure of FVa2 bound to the benzamidine-inhibited proteinase. Our results suggest that the acidic A2-B domain linker is involved in major interactions with thrombin during cofactor activation, with its more NH(2)-terminal hirudin-like sequence playing a critical role. Modeling experiments indicate that FVa2, and likely also FVa3, wrap around thrombin in productive thrombin*FV complexes that cover a large surface of the activator to engage the active site. Structural basis of thrombin-mediated factor V activation: the Glu666-Glu672 sequence is critical for processing at the heavy chain-B domain junction.,Corral-Rodriguez MA, Bock PE, Hernandez-Carvajal E, Gutierrez-Gallego R, Fuentes-Prior P Blood. 2011 May 9. PMID:21555742[25] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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