Question

Explain how epinephrine regulates the breakdown of glycogen.

can you have clear steps & explanations  

Answer 1

Answer: The key enzyme in the regulation of glycogen metabolism for regulation of glycogenesis is - Glycogen synthase and for Glycogenolysis it is --- Glycogen phosphorylase. Insulin and glycogen controls these hormones by phosphorylation and dephosphorylation.The enzyme gylcogen synthase is active in dephosphorylated state while glycogen phosphorylase is active in its phosphorylated state.Insulin favours the glucose utilization meanss it decreases the blood glucose level while glucagon , growth hormone and glucacorticoid they all increases blood glucose level.

Pathway of regulation:

Step 1:Glycogen in liver/ glycogen in Epinephrin in muscles they attaches to the receptor and they act via Cyclic AMP so they cause the formation of Adenylcyclase. This Adenylcyclase will convert ATP into cyclic AMP(cAMP)

Step 2: Cyclic AMP activates the Protein kinase(inactive form) to active form protein kinase(PKa). This active PK stimulate the Phosphorylase Kinase(inactive) to active form of Phosphorylase Kinase.

Step3: Active form of Phosphorylase Kinase activate the glycogen phosphorylase via. phosphorylation . As active Glycogen phosphorylase is is a key enzyme in glycogenolysis so it stimulate the breakdon of glycogen into glucose and increases the blood glucose level. Calcium also activates the Glycogen phosphorylase and increases the blood glucose level.

So via Glycogen and epinephrin there is stimulation of glycogenolysis which increass the blood glucose level and inhibit the glycogen synthesis.