Vitamin K is a cofactor in:

Ans. (A) Carboxylation(Ref: Katzung 10/e p549, 550; KDT 8/e p667)Vitamin K is involved in activation of various clotting factors (like II, VII, IX and X) as well as anti-clotting proteins (like protein C and S). It carries out the final step in activation of these factors i.e. gamma carboxylation of glutamate residues in these factors.