cAMP-dependent protein kinase regulatory subunit (PRKAR)

The cAMP-dependent protein kinase (PKA) regulatory subunits are essential components of the PKA holoenzyme, acting as the primary sensors for the second messenger cAMP in eukaryotic cells [UniProt: P10644, P31323]. These subunits exist in four distinct isoforms—RIα, RIβ, RIIα, and RIIβ—which regulate the localization and activation threshold of the kinase complex through interactions with A-kinase anchoring proteins (AKAPs) [PubMed: 12191413]. Upon binding of cAMP to the regulatory subunits, a conformational change occurs that triggers the dissociation of the PKA holoenzyme, releasing active catalytic subunits to phosphorylate downstream targets involved in metabolism, gene expression, and cell cycle control [PubMed: 10751400]. Mutations in the PRKAR1A gene are a known cause of Carney complex, a hereditary multi-neoplasia syndrome, and are also implicated in Cushing syndrome and acrodysostosis [OMIM: 160980, PubMed: 24571740]. Because of their central role in signaling, these subunits are targets for cAMP analogs like 8-Br-cAMP and are being explored for therapeutic potential in oncology and cardiovascular medicine [PubMed: 15688010]. However, the ubiquitous expression of PKA subunits presents a significant challenge for drug development, as systemic modulation can lead to widespread off-target effects [PubMed: 21854901].

Other names

Protein kinase A regulatory subunitPKA regulatory subunitcAMP-dependent protein kinase regulatory subunit type I-alphacAMP-dependent protein kinase regulatory subunit type I-betacAMP-dependent protein kinase regulatory subunit type II-alphacAMP-dependent protein kinase regulatory subunit type II-beta

Binding of cyclic AMP (cAMP) to the regulatory subunits induces a conformational change that leads to the dissociation of the PKA holoenzyme, thereby releasing active catalytic subunits to phosphorylate target proteins [PubMed: 10751400].