Some Clotting Factors Contain G-Carboxyglutamate

Some clotting factors contain g-carboxyglutamate.The function of this unusual amino acid residue in the clotting factors is to bind calcium and to:

A) Increase the substrate specificity of the clotting factors, thereby preventing the incidental cleavage of other proteins.
B) Bind the clotting factors to exposed components of the extracellular matrix.
C) Serve as a feedback mechanism that makes the activated clotting factors sensitive to protease inhibitors.
D) Create cleavage sites for proteolytic activations during zymogen processing.
E) Bind the clotting factors to activated platelets.