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MBBS QUESTION #10331
Question 1
Vitamin K serves as an essential cofactor for post-translational gamma-carboxylation of glutamate residues on which clotting factors, explaining both its role in normal coagulation and the mechanism of warfarin's anticoagulant action?
  • Factors II, VII, IX, and X, along with proteins C and S✔️
  • Factor VIII exclusively
  • Fibrinogen exclusively
  • Von Willebrand factor exclusively
Correct Answer Explanation
Gamma-carboxylation, dependent on vitamin K, allows factors II, VII, IX, X (and the anticoagulant proteins C and S) to bind calcium and phospholipid surfaces necessary for their coagulation function; warfarin inhibits vitamin K epoxide reductase, blocking this carboxylation step and reducing functional levels of these factors.