This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Clotting system, Subject name: Pathology
Vitamin required for bone formation as well as coagulation cascade is: 
Select and explain. 
A. A, B. D, C. E, D. K
D: K
Answer: D: K 
Explanation: 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. Clotting factors contain 4 to 6 g-carboxyglutamate residues:- Eg- II VII IX X Protein C Protein S Protein Z Osteocalcin Transthyretin (Prealbumin)