cd05123

Catalytic domain of AGC family Protein Serine/Threonine Kinases; Serine/Threonine Kinases (STKs), AGC (Protein Kinases A, G and C) family, catalytic (c) domain. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The AGC family 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). Members of this family include cAMP-dependent Protein Kinase (PKA), cGMP-dependent Protein Kinase (PKG), Protein Kinase C (PKC), Protein Kinase B (PKB), G protein-coupled Receptor Kinase (GRK), Serum- and Glucocorticoid-induced Kinase (SGK), and 70 kDa ribosomal Protein S6 Kinase (p70S6K or S6K), among others. AGC kinases share an activation mechanism based on the phosphorylation of up to three sites: the activation loop (A-loop), the hydrophobic motif (HM) and the turn motif. Phosphorylation at the A-loop is required of most AGC kinases, which results in a disorder-to-order transition of the A-loop. The ordered conformation results in the access of substrates and ATP to the active site. A subset of AGC kinases with C-terminal extensions containing the HM also requires phosphorylation at this site. Phosphorylation at the HM allows the C-terminal extension to form an ordered structure that packs into the hydrophobic pocket of the catalytic domain, which then reconfigures the kinase into an active bi-lobed state. In addition, growth factor-activated AGC kinases such as PKB, p70S6K, RSK, MSK, PKC, and SGK, require phosphorylation at the turn motif (also called tail or zipper site), located N-terminal to the HM at the C-terminal extension. AGC kinases regulate many cellular processes including division, growth, survival, metabolism, motility, and differentiation. Many are implicated in the development of various human diseases.