In a G-protein-coupled receptor (GPCR) pathway, a ligand binds to the receptor and activates a G protein, which then activates adenylyl cyclase. What is the most likely direct role of cyclic AMP (cAMP) in this pathway?

Core Concept

cAMP is a classic second messenger produced by adenylyl cyclase. It diffuses through the cytoplasm and activates protein kinase A (PKA), which then phosphorylates various target proteins, propagating and amplifying the signal.