Question

In the clotting mechanism pathway, thrombin activates factor

• A. XI, VIII, V
• B. XI, IX, X
• C. VIII, X, V
• D. IX, VIII, X

Answer 1

The correct option is A XI, VIII, V

Thrombin is a serine protease, that in humans is encoded by the F${}_2$ gene. Thrombin is obtained by the proteolytic cleavage of prothrombin in the coagulation cascade which results in reduction of blood loss. Thrombin now acts as a serine protease that converts soluble fibrinogen to insoluble strands of fibrin and also catalyzes many other coagulation related reactions. So, once activated, thrombin acts to convert factor XI to XIa, VIII to VIIIa, fibrinogen to fibrin and XIII to XIIIa.
Thus, the correct answer is option (A).