MOD_PKA_1

PKA belongs to the large set of related AGC kinases having a preference for phosphorylating basophilic sites. cAMP-dependent protein kinase A (PKA) is the major target for cAMP action in eukaryotic cells. The enzyme is allosterically activated by binding of cAMP to two regulatory (R) subunits, which induces dissociation of two catalytic (C) subunits. The active kinase is then free to phosphorylate substrates on serine, or less commonly threonine residues in recognition motifs. The enzyme acts on a wide number of proteins involved in several biochemical processes. These include glucose metabolism (via activation and inactivation of glycogen phosphorylase b and glycogen synthase, respectively), fatty acid synthesis (via acetyl-coA carboxylase), and pyruvate oxidation (via pyruvate dehyrogenase complex). This is therefore a vital signaling enzyme in a number of metabolic processes, affecting many cell functions by activating or inactivating substrate proteins in the presence of cAMP.