Glycogen synthesis and breakdown takes place in the same cell, having enzymes necessary for both the pathways. Why the glucose-6-phosphate, freshly synthesized during glycogenesis in cytoplasm of hepatocytes, is not immediately degraded by the enzyme glucose!6-phosphatase?
(A) The thermodynamics does not or such a reaction to occur (B) Glucose-6-phosphatase is present in the endoplasmic reticulum and cannot act on glycogen formed in the cytoplasm (C) Glycogenesis and glycogenolysis are tightly regulated such that enzymes of only one of those is present at a time. (D) Steric hindrance due to albumin
(B) Ans: B. Glucose-6-phosphatase is present in the endoplasmic reticulum and cannot act on glycogen formed in the cytoplasm(Ref Harper 30/e p178)Glucose-6-phosphate:Formed in cytoplasm of hepatocytes.Glucose-6-phosphatase:Present in lumen of smooth endoplasmic reticulum of cell.Reaction does not take place until gluconeogenesis is ored.Glucose-6-phosphatase catalyzes hydrolysis of glucose-6-phosphate in liver - Expos glucose a increases blood glucose concentration