PKA Isoforms

The cAMP-dependent protein kinase (PKA) holoenzyme is composed of two regulatory and two catalytic subunits, designated PKA R and PKA C, respectively. Upon PKA R subunit binding to the second messenger cAMP, active PKA C subunits are released, initiating a phosphorylation cascade that regulates such cellular functions as metabolism, ion transport, and gene transcription. Catalytic PKA subunit isoforms, Cα, Cβ and, in humans, Cγ, have been identified.