<prompt> Post-translational modification of clotting factors requiresVitamin AVitamin BVitamin EVitamin K  <response>: Vitamin K has an impoant role in the blood clotting process. It brings about the posttranslational modification of ceain blood clotting factors clotting factor II prothrombin, factor VII SPCA factor IX Christmas factor factor X Stua prower factor Vitamin K is required for the post-translational carboxylation of glutamic acid Gamma Carboxylation, which is necessary for calcium binding to g carboxylated proteins clotting factors are synthesized as inactive precursors zymogens in the liver ref DM Vasudevan 8th ed page 462 