AP BIOLOGY

Detailed explanation-1: -The alpha subunit then binds to adenylyl cyclase, which converts ATP into cAMP. cAMP then binds to protein kinase A, which activates it.

Detailed explanation-2: -To activate the enzyme, two molecules of cAMP bind to the regulatory subunits and trigger conformational changes that dissociate the complex, resulting in activation of the catalytic subunits of PKA for subsequent phosphorylation of substrates in various subcellular compartments.

Detailed explanation-3: -Within each cell, cAMP may activate different proteins; however, its most well-known mode of action is through binding to PKA. When not bound to cAMP, PKA is an inactive tetramer of two regulatory and two catalytic subunits.