Regulates G protein-coupled receptor signaling cascades. Inhibits signal transduction by increasing the GTPase activity of G protein alpha subunits, thereby driving them into their inactive GDP-bound form. The RGS6/GNB5 dimer enhances GNAO1 GTPase activity (PubMed:10521509). Interacts with GNB5 (PubMed:12761221, PubMed:10339615, PubMed:10521509). Interacts with RGS7BP, leading to regulate the subcellular location of the heterodimer formed with GNB5 (By similarity). Interacts with GNAI1 (PubMed:18434541). Interaction with GNB5 mediates translocation to the nucleus. Additional isoforms seem to exist. The RGS domain interacts avidly with Galpha and mediates the acceleration of Galpha-mediated GTP hydrolysis.