Transferases;
Transferring phosphorus-containing groups;
Protein-serine/threonine kinases
BRITE hierarchy

ATP:protein Ser/Thr-phosphotransferase (3',5'-cAMP-dependent)

ATP + a [protein]-(L-serine/L-threonine) = ADP + a [protein]-(L-serine/L-threonine) phosphate [RN:R00162]

R00162
Reaction

ATP [CPD:C00002];
[protein]-(L-serine/L-threonine)

This eukaryotic enzyme recognizes the sequence -Arg-Arg-X-Ser*/Thr*-Hpo, where * indicates the phosphorylated residue and Hpo indicates a hydrophobic residue.The inactive holoenzyme is a heterotetramer composed of two regulatory (R) subunits and two catalytic (C) subunits. Each R subunit occludes the active site of a C subunit and contains two binding sites for 3',5'-cyclic-AMP (cAMP). Binding of cAMP activates the enzyme by causing conformational changes that release two free monomeric C subunits from a dimer of the R subunits, i.e. R2C2 + 4 cAMP = R2(cAMP)4 + 2 C. Activity requires phosphorylation of a conserved Thr in the activation loop (T-loop) sequence (Thr198 in human Calpha; Thr224 in budding yeast Tpk2), installed by auto-phosphorylation or by the 3-phosphoinositide-dependent protein kinase-1 (PDPK1). Certain R2C2 combinations can be localized to particular subcellular regions by their association with diverse species of 'A Kinase-Anchoring Proteins' (AKAPs). The enzyme has been characterized from many organisms. Humans have three C units (Calpha, Cbeta, and Cgamma) encoded by the paralogous genes PRKACA, PRKACB and PRKACG, respectively, and four R subunits (R1alpha, RIbeta, RIIalpha and RIIbeta), encoded by PKRAR1A, PKRAR1B, PKRAR2A and PKRAR2B, respectively. Yeast (Saccharomyces cerevisiae) has three C subunits (Tpk1, Tpk2, and Tpk3) encoded by the paralogous genes TPK1, TPK2 and TPK3, respectively, and a single R subunit (Bcy1) encoded by the BCY1 gene. Some validated substrates of the enzyme include cAMP-response element-binding protein (CREB), phosphorylase kinase alpha subunit (PHKA), and tyrosine 3-monooxygenase (TH) in mammals; Adr1, Whi3, Nej1, and Pyk1 in yeast.

EC 2.7.11.11 created 2005 (EC 2.7.1.37 part-incorporated 2005), modified 2022