cAMP-dependent pathway. Molecular model of a G-alpha protein (light blue) bound to the enzyme adenylyl cyclase (darker blue). GTP (guanosine triphosphate, yellow) has bound to the G-alpha protein, activating it and breaking it away from its G-protein complex (not seen) allowing it to bind to adenylyl cyclase. The binding of the G-alpha subunit activates adenylyl cyclase, which catalyses the conversion of ATP (adenosine triphosphate, red, centre) to cyclic adenosine monophosphate (cAMP, red bottom right of ATP) and pyrophosphate (red, above cAMP). cAMP regulates numerous cell functions.