Question

Compare and contrast the action of epinephrine vs glucagon binding and signaling from its target GPCR (G-protein coupled receptors) in order to regulate glucose metabolism under stress vs rest conditions.

Answer 1

Epinephrine and glucagon role in glucose metabolism is slightly similar in a way that they both increases the blood sugar level when it is low. Under stress conditions, epinephrine acts and increases blood sugar level through release of glucose from liver cells while glucagon is released from pancreatic cells and increases glucose level by breaking down of glycogen.

Epinephrine binds to its receptor which is G- protein coupled receptor. As it binds, receptor is activated. It activates inturn adenylate cyclase and produces cAMP. This activates the downstream proteins and increases the glucose formation and release from hepatocytes.

Glucagon upon binding to glucagon G- protein coupled receptor, cAMP is produces which activates protein kinase A. This PKA activates phophorylases enzymes. This signal cascade leads to breakdown of glycogen to glucose.