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, VII, IX, X 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