Catalytic domain of the Serine/Threonine Kinase, beta-adrenergic receptor kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The beta-ARK group is composed of GRK2, GRK3, and similar proteins. GRK2 and GRK3 are both widely expressed in many tissues, although GRK2 is present at higher levels. They contain an N-terminal RGS homology (RH) domain, a central catalytic domain, and C-terminal pleckstrin homology (PH) domain that mediates PIP2 and G protein betagamma-subunit translocation to the membrane. GRK2 (also called beta-ARK or beta-ARK1) is important in regulating several cardiac receptor responses. It plays a role in cardiac development and in hypertension. Deletion of GRK2 in mice results in embryonic lethality, caused by hypoplasia of the ventricular myocardium. GRK2 also plays important roles in the liver (as a regulator of portal blood pressure), in immune cells, and in the nervous system. Altered GRK2 expression has been reported in several disorders including major depression, schizophrenia, bipolar disorder, and Parkinsonism. GRKs phosphorylate and regulate G protein-coupled receptors (GPCRs), the largest superfamily of cell surface receptors which regulate some part of nearly all physiological functions. Phosphorylated GPCRs bind to arrestins, which prevents further G protein signaling despite the presence of activating ligand. The beta-ARK subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
Jiyao W et al.(2023). "The conserved domain database in 2023.",