The A-kinase anchoring proteins or A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins, which have the common function of binding to the regulatory subunit of protein kinase A (PKA) and confining the holoenzyme to discrete locations within the cell.[1][2] At least 20 AKAPs have been cloned.[3] There are at least 50 members, often named after their molecular mass.
AKAPs act as scaffold proteins wherein they bind PKA and other signaling proteins and physically tether these multi-protein complexes to specific locations, such as the nucleus, in cells.[2] This allows specific targeting of substrates to be regulated by phosphorylation (by PKA) and dephosphorylation (by phosphatases).[2] The dimerization and docking (D/D) domain of the regulatory subunit dimer of PKA binds with the A-kinase binding (AKB) domain (an amphipathic helix) of AKAP. The AKAPs also bind other components, including; phosphodiesterases (PDEs) which break down cAMP, phosphatases which dephosphorylate downstream PKA targets and also other kinases (PKC and MAPK). Some AKAPs are able to bind both regulatory subunits (RI & RII) of PKA and are dual-specific AKAPs (D-AKAP1 and D-AKAP2).