Cyclic AMP-independent activation of glycogen breakdown in hepatocytes occurs as a result of the binding of which of the following?

Question

Quizplus · Accepted Answer

Epinephrine binding to α1-adrenergic receptors activates glycogen breakdown in hepatocytes through a pathway that does not involve cyclic AMP, but rather involves the phosphoinositide pathway leading to increased intracellular calcium levels. When epinephrine binds α-adrenergic receptors, there is an activation of the membrane-associated enzyme PLC-β. PLC-β hydrolyzes membrane PIP₂ into DAG and IP₃. The IP₃ then binds to receptors present in membranes of the endoplasmic reticulum (ER) resulting in release of stored calcium ion. The released calcium binds to the calmodulin subunit of glycogen synthase-phosphorylase kinase, resulting in activation of this regulatory enzyme. The net effect is enhanced activity of phosphorylase and inhibited activity of glycogen synthase

Cyclic AMP-Independent Activation of Glycogen Breakdown in Hepatocytes Occurs as a Result