Intracellular targeting of the type-I alpha regulatory subunit of cAMP-dependent protein kinase.

The specificity of cyclic adenosine monophosphate (cAMP)-mediated signaling events is achieved by the composition and biochemical properties of the different cAMP-dependent protein kinase holoenzymes (PKAI and II) and by compartmentalization of PKA to discrete subcellular locations. Intracellular localization is mediated by interaction with A-kinase anchoring proteins (AKAPs) that recruit PKAII close to its substrates and to sites where it can respond optimally to local changes in intracellular cAMP concentration, thereby directing and amplifying the effects of cAMP. This review presents recent evidence that indicates that specific AKAPs mediate PKAI anchoring through interaction with its regulatory subunit RI alpha, notably at the neuromuscular junction of skeletal muscle.