Study note
BiochemistryMicronutrients: Vitamins & Minerals

γ-Carboxyglutamate in blood-clotting proteins

THE CONTEXT
γ-Carboxyglutamate residues support calcium binding and membrane attachment of several proteins in the blood-clotting system.

Proteins and function

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Prothrombin, factors VII, IX, and X, and proteins C and S each contain 4 to 6 γ-carboxyglutamate residues.
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γ-Carboxyglutamate chelates calcium ions, permitting blood-clotting proteins to bind to membranes.

Vitamin K deficiency and warfarin

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In vitamin K deficiency or in the presence of warfarin, an abnormal prothrombin precursor called preprothrombin is released into the circulation.
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This precursor contains little or no γ-carboxyglutamate and cannot chelate calcium.
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