This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Vitamin k is responsible for the carboxylation of which amino acid in the clotting factors 
Select and explain. 
A. Aspaate, B. Glutamate, C. Proline, D. Lysine
B: Glutamate
Answer: B: Glutamate 
Explanation: Ref Robbins 8/e p 119;9/e p119 The vitamin K-dependent carboxylase carries out the posttranslational modification of specific glutamate residues in proteins togamma-carboxy glutamic acid (Gla) in the presence of reduced vitamin K, molecular oxygen, and carbon dioxide.