Activation of adenylate cyclase by epinephrine or glucagon produces cAMP, which promotes the dissociation of cAMP-dependent protein kinase (R2C2) to give free catalytic monomers (C). C is the protein kinase, which phosphorylates other proteins.

Proteins phosphorylated by cAPK include: glycogen phosphorylase b kinase (activates), PFK-2 (inactivates), acetyl CoA carboxylase (inactivates), hormone-sensitive triacylglycerol lipase (activates), glycogen synthase (inactivates).