Which one of the following amino acid residue is carboxylated by Vitamin K?: (A) Aspaate, (B) Glutamate, (C) Tryptophan, (D) Tyrosine
Answer is B. Vitamin K is the cofactor for g-carboxylation of glutamate residues of protein to produce g-carboxy glutamate (gla). This process is known as Vitamin K epoxide cycle (as illustrated in the image below).