This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which of the following enzyme is common between glycogenesis and glycogenolysis? 
Select and explain. 
A. Glycogen synthase, B. Glycogen phosphorylase, C. Glucan transferase, D. Phosphoglucomutase
D: Phosphoglucomutase
Answer: D: Phosphoglucomutase 
Explanation: Ans: D.PhosphoglucomutasePhosphoglucomutase enzyme is common between glycogenesis & glycogenolysis.Reaction catalyzed by phosphoglucomutase is reversible.Hence, glucose 6-phosphate can be formed from glucose I-phosphate.In liver & kidney, (not in muscle) glucose 6-phosphatase hydrolyzes glucose 6-phosphate a glucose a Increases blood glucose concentration.(Ref Harper's 29/e p180; Harper 30/e p176, 177, 28/e p158, 333).