cd12101: DD_RIalpha_PKA (this model, PSSM-Id:213048 is obsolete and has been replaced by 438522)
Dimerization/Docking domain of the Type I alpha Regulatory subunit of cAMP-dependent protein kinase
cAMP-dependent protein kinase (PKA) is a serine/threonine kinase (STK), catalyzing the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The inactive PKA holoenzyme is a heterotetramer composed of two phosphorylated and active catalytic subunits with a dimer of regulatory (R) subunits. Activation is achieved through the binding of the important second messenger cAMP to the R subunits, which leads to the dissociation of PKA into the R dimer and two active subunits. There are two classes of R subunits, RI and RII; each exists as two isoforms (alpha and beta) from distinct genes. These functionally non-redundant R isoforms allow for specificity in PKA signaling. RI subunits are pseudo-substrates as they do not contain a phosphorylation site in their inhibitory site unlike RII subunits. RIalpha is the key regulatory subunit responsible for maintaining cAMP control of the catalytic subunit. RIalpha function is required for normal development as its deletion is embryonically lethal due to failed cardiac morphogenesis. The R subunit contains an N-terminal dimerization/docking (D/D) domain, a linker with an inhibitory sequence, and two c-AMP binding domains. The D/D domain dimerizes to form a four-helix bundle that serves as a docking site for A-kinase-anchoring proteins (AKAPs), which facilitates the localization of PKA to specific sites in the cell. PKA is present ubiquitously in cells and interacts with many different downstream targets. It plays a role in the regulation of diverse processes such as growth, development, memory, metabolism, gene expression, immunity, and lipolysis.
Jiyao W et al.(2023). "The conserved domain database in 2023.",