Vitamin K–Dependent Proteins

Vitamin K–dependent coagulation-factor proenzymes (factors II, VII, IX, and X) contain γ-carboxyglutamic acid,1 2 3 an amino acid formed by the post-translational action of a vitamin K–dependent γ-glutamyl carboxylase on specific glutamyl residues.4 Residues of γ-carboxyglutamic acid are located near the amino-terminal portions of these proteins; factors II (prothrombin) and VII each possess 10 such residues per molecule, whereas factors IX and X each possess 12. There is a striking sequence homology in the amino-terminal portions of these factors, especially with respect to the positions of the γ-carboxyglutamic acid residues.The discovery of γ-carboxyglutamic acid, after decades of speculation about the actions . . .