PKAcb, Active

Most of the effects of cAMP are mediated through the phosphorylation of target proteins on serine or threonine residues by the cAMP-dependent protein kinase (PKA). The inactive holoenzyme of AMPK is a tetramer composed of two regulatory and two catalytic subunits. The mammalian catalytic subunit has been shown to consist of three PKA gene products: C-α, C-β, and C-γ. Two PKA isoforms exist, designated types I and II, which differ in their dimeric regulatory subunits, designated RI and RII, respectively. Furthermore, there are at least four different regulatory subunits: RI-α, RI-β, RII-α, and RII-β. The cAMP causes the dissociation of the inactive holoenzyme into a dimer of regulatory subunits bound to four cAMP and two free monomeric catalytic subunits. The catalytic subunit C-β of PKA (PKAcb) is a member of the Ser/Thr protein kinase family and is a catalytic subunit C-β of AMPK. Berube et al. assigned the PKAcb to human chromosome 1 by Southern blot analysis of somatic cell hybrids (1) and Simard et al located it to 1p36.1 by in situ hybridization (2).