FunctionInhibits signal transduction by increasing the GTPase activity of G protein alpha subunits thereby driving them into their inactive GDP-bound form. Binds to G(t)-alpha. Involved in phototransduction; key element in the recovery phase of visual transduction.
Tissue specificityHighly expressed in the caudate and putamen, lower levels found in the hypothalamus and nucleus accumbens and very low levels in cerebellum. Not expressed in globus pallidus or cingulate cortex. Isoform 2 is expressed predominantly in pineal gland and retina. Isoform 3 is expressed in retina (abundant in photoreceptors).
Involvement in diseaseDefects in RGS9 are a cause of prolonged electroretinal response suppression (PERRS) [MIM:608415]; also known as bradyopsia. PERRS is characterized by difficulty adjusting to sudden changes in luminance levels mediated by cones.
Sequence similaritiesContains 1 DEP domain. Contains 1 G protein gamma domain. Contains 1 RGS domain.
DomainIn photoreceptor cells the DEP domain is essential for targeting RGS9 to the outer rod segments.
Post-translational modificationsRetinal isoform 3 is light-dependent phosphorylated at 'Ser-478'. Phosphorylation is decreased by light exposition.
Cellular localizationMembrane. Isoform 3 is targeted to the membrane via its interaction with RGS9BP.