Which molecule acts as a second messenger in the cascade by which epinephrine stimulates the activation of the enzyme glycogen phosphorylase?
A) Adenosine
B) Caffeine
C) Citric acid
D) Cyclic AMP
E) Adenylyl cyclase

Question

Quizplus · Accepted Answer

The molecule that acts as a second messenger in the cascade leading to the activation of glycogen phosphorylase is cyclic AMP (cAMP). Epinephrine binds to a G protein-coupled receptor on the surface of the target cell, leading to the activation of adenylyl cyclase, an enzyme that synthesizes cAMP from ATP. cAMP then activates protein kinase A, which in turn activates glycogen phosphorylase, leading to the breakdown of glycogen into glucose. Therefore, the correct answer is D, cyclic AMP.

Which Molecule Acts as a Second Messenger in the Cascade