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Catalytic domain of the Serine/Threonine Kinase, G protein-coupled Receptor Kinase 6 STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. GRK6 is widely expressed in many tissues and is expressed as multiple splice variants with different domain architectures. It is post-translationally palmitoylated and localized in the membrane. GRK6 plays important roles in the regulation of dopamine, M3 muscarinic, opioid, and chemokine receptor signaling. It also plays maladaptive roles in addiction and Parkinson's disease. GRK6-deficient mice exhibit altered dopamine receptor regulation, decreased lymphocyte chemotaxis, and increased acute inflammation and neutrophil chemotaxis. 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 GRK6 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.
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