In the signal cascade triggered by epinephrine in liver cells, glycogen phosphorylase is
A) inactivated and binds to glucose.
B) activated and releases glucose.
C) inactivated and produces glycogen.
D) inactivated by protein kinase A.
E) activated by cyclic AMP.

Question

Quizplus · Accepted Answer

Epinephrine activates the G protein-coupled receptor, leading to activation of adenylyl cyclase and production of cyclic AMP. Cyclic AMP then activates protein kinase A, which in turn activates glycogen phosphorylase. Active glycogen phosphorylase breaks down glycogen into glucose for energy use. Therefore, glycogen phosphorylase is activated and releases glucose in liver cells in response to epinephrine.

In the Signal Cascade Triggered by Epinephrine in Liver Cells