cd05580: STKc_PKA (this model, PSSM-Id:173671 is obsolete and has been replaced by 270732)
Catalytic domain of the Protein Serine/Threonine Kinase, cAMP-dependent protein kinase
Serine/Threonine Kinases (STKs), cAMP-dependent protein kinase (PKA) subfamily, catalytic (c) subunit. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The PKA subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase (PI3K). This subfamily is composed of the cAMP-dependent proteins kinases, PKA and PRKX. The inactive PKA holoenzyme is a heterotetramer composed of two phosphorylated and active catalytic (C) 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 C subunits. 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.