Inhibits signal transduction by increasing the GTPase activity of G protein alpha subunits thereby driving them into their inactive GDP-bound form. Binds to GNAT1. Involved in phototransduction; key element in the recovery phase of visual transduction. Heterodimer with GNB5. Interacts with RGS7BP, leading to regulate the subcellular location of the heterodimer formed with GNB5. Component of the RGS9-1-Gbeta5 complex composed of RGS9 (RGS9-1), Gbeta5 (GNB5) and RGS9BP (Probable). Interacts with PDE6G and GNAT1 (PubMed:11234020). Targeted to the membrane via its interaction with RGS9BP. Photoreceptor outer segments. Phosphorylation is decreased by light exposition.