Inhibits 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 (By similarity). Heterodimer with Gbeta5. Interacts with RGS7BP, leading to regulate the subcellular location of the heterodimer formed with Gbeta5. Component of the RGS9-1-Gbeta5 complex composed of RGS9 (RGS9-1), Gbeta5 (GNB5) and RGS9BP (Probable). Targeted to the membrane via its interaction with RGS9BP. Phosphorylation is decreased by light exposition.