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Vitamin K Cycle
Hepatic cycle of vitamin K oxidation and reduction that supports γ-glutamyl carboxylation of vitamin K-dependent proteins (factors II, VII, IX, X; proteins C and S; osteocalcin; matrix Gla protein).
Also: VKORC1 cycle
Reduced vitamin K (hydroquinone) is a cofactor for γ-glutamyl carboxylase, which carboxylates glutamate residues on target proteins (necessary for Ca2+ binding). The 2,3-epoxide product is recycled to the quinone form by vitamin K epoxide reductase (VKORC1), the target of warfarin. VKORC1 polymorphisms account for substantial inter-individual variation in warfarin dose requirements.
How one textbook covers it
Modern Nutrition in Health and Disease, 12th ed. — Ch 19: Vitamin K
Reduced vitamin K (hydroquinone) is a cofactor for γ-glutamyl carboxylase, which carboxylates glutamate residues on target proteins (necessary for Ca2+ binding). The 2,3-epoxide product is recycled to the quinone form by vitamin K epoxide reductase (VKORC1), the target of warfarin. VKORC1 polymorphisms account for substantial inter-individual variation in warfarin dose requirements.
Related terms
Matrix Gla protein, Osteocalcin, Vitamin K, Warfarin