Thrombin Activation of Factor XI on Activated Platelets Requires the Interaction of Factor XI and Platelet Glycoprotein Ibα with Thrombin Anion-binding Exosites I and II, Respectively
نویسندگان
چکیده
منابع مشابه
Thrombin activates factor XI on activated platelets in the absence of factor XII.
Thrombin can activate factor XI in the presence of dextran sulfate or sulfatides. However, a physiological cofactor for thrombin activation of factor XI has not been identified. We examined this question in a cell-based, tissue factor-initiated model system. In the absence of factor XII, factor XI enhanced thrombin generation in this model. The effect on thrombin generation was reproduced by 2 ...
متن کاملWhen and where is factor XI activated by thrombin?
To the Editor. bound to the clot is protected and is no longer subject to inhibition by the competitive substrate, fibrinogen, and is able to catalyze the feedback to activate factor XI and enhance the intrinsic cascade. The pathway by which factor XI is initially activated is still unclear, because the autoactivation of factor is completely inhibited by fibrinogen and high molecular weight kin...
متن کاملActivated factor V is a cofactor for the activation of factor XI by thrombin in plasma.
The mechanism by which the intrinsic pathway of coagulation contributes to physiological hemostasis is enigmatic. Thrombin activates factor XI, a key zymogen in this pathway, which leads to increased thrombin generation. As thrombin-dependent activation of factor XI in vitro is relatively inefficient, we hypothesized that a physiological cofactor supports this reaction in a plasma environment. ...
متن کاملDefective binding of factor XI-N248 to activated human platelets.
Variants of factor XI containing Gln226 to Arg (Q226 to R) and Ser248 to Asn (S248 to N) substitutions were first identified in an African American family with a history of excessive bleeding. The substitutions have recently been identified in unrelated individuals, suggesting they are relatively common. Both amino acids are located in the third apple domain of factor XI, an area implicated in ...
متن کاملThrombin-mediated feedback activation of factor XI on the activated platelet surface is preferred over contact activation by factor XIIa or factor XIa.
To study the pathways for initiation of intrinsic blood coagulation, activated human platelets were compared with dextran sulfate as surfaces for factor XI activation by factor XIIa, factor XIa, or thrombin. Activated gel-filtered platelets promoted the activation of factor XI (60 nm) by thrombin (0.02-10 nm, EC(50) approximately 100 pm, threshold concentration approximately 10 pm) at initial r...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 2003
ISSN: 0021-9258
DOI: 10.1074/jbc.m306925200