Question

You are faced with an imminent threat to your safety and decide to RUN for your life! As
part of the flight/fight response activation of your HPA axis lead to an increase in the
hormone adrenalin. Discuss how adrenalin binding to a receptor on hepatocyte cells can
ultimately lead to the breakdown of glycogen. Your answer should include details of the
receptor activation at the plasma membrane, signal transduction in the cytoplasm leading to
activation of glycogen phosphorylase

(can u please explain briefly for 20 Mark's.)

Answer 1

Adrenalin binds to the β-adrenergic receptor and also to the 7TM α-adrenergic receptor on the hepatocyte plasma membrane, which then activates phospholipase C and, hence, initiates the phosphoinositide cascade. Phosphatidyl inositol Bisphosphate is hydrolyzed by Phospholipase C.The consequent rise in the level of inositol 1,4,5-trisphosphate induces the release of Ca2+ from endoplasmic reticulum stores. Binding of Ca2+ to calmodulin leads to a partial activation of phosphorylase kinase.