Intrinsic tenase complex (factor VIIIa–factor IXa complex) (Intrinsic tenase; sometimes called VIIIa–IXa complex)

The intrinsic tenase complex is a multiprotein enzyme assembly involved in the intrinsic pathway of the blood coagulation cascade. It consists of activated coagulation factor VIIIa (a cofactor) and factor IXa (a serine protease), bound together on phospholipid surfaces in the presence of calcium ions (Ca2+)[2][5][6]. This complex markedly accelerates the conversion of coagulation factor X to its activated form, factor Xa, which is essential for the downstream generation of thrombin and fibrin clot formation[3][4][6]. Deficiencies in factor VIII (hemophilia A) or factor IX (hemophilia B) disrupt tenase function, resulting in impaired clot formation and bleeding disorders. The activity of this complex is targeted by replacement therapies in hemophilia, and its dysregulation can predispose to thrombotic or bleeding complications[1][2][6].

Other names

Intrinsic tenase complexfactor VIIIa–factor IXa complexVIIIa receptor complexblood coagulation factor VIIIa–IXa complextenase (intrinsic)VIIIa:IXa complex

Replacement (factor VIII or IX replacement in hemophilia); Mimetic/agonist (emicizumab acts as a FVIII mimetic); Inhibition (protein C, antithrombin inactivate or regulate complex)