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Regulator of G protein signaling (RGS) domain found in the RGS20 protein The RGS (Regulator of G-protein Signaling) domain is an essential part of the RGS20 protein (also known as RGSZ1), a member of the RZ subfamily of the RGS protein family. They are a diverse group of multifunctional proteins that regulate cellular signaling events downstream of G-protein coupled receptors (GPCRs). RGS proteins play critical regulatory roles as GTPase activating proteins (GAPs) of the heterotrimeric G-protein G-alpha-subunits. Deactivation of G-protein signaling is controlled by the RGS domain, which accelerates GTPase activity of the alpha subunit by hydrolysis of GTP to GDP resulting in reassociation of the alpha-subunit with the beta-gamma-dimer and inhibition of downstream activity. As a major G-protein regulator, the RGS domain containing proteins are involved in many crucial cellular processes such as regulation of intracellular trafficking, glial differentiation, embryonic axis formation, skeletal and muscle development, and cell migration during early embryogenesis. The RZ subfamily of RGS proteins include RGS17, RGS19 (former GAIP), and the splice variant of RGS20, Ret-RGS. RGS20 is expressed exclusively in brain, with the highest concentrations in the temporal lobe and the caudate nucleus and may play a role in signaling regulation in these brain regions. RGS20 acts as a GAP of both G-alpha-z and G-alpha-I and controls signaling in the mu opioid receptor pathway.
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