Members of this family adopt a structure consisting of twelve helices that fold into a compact domain that contains the overall structural scaffold observed in other RGS proteins and three additional helical elements that pack closely to it. Helices 1-9 comprise the RGS (pfam00615) fold, in which helices 4-7 form a classic antiparallel bundle adjacent to the other helices. Like other RGS structures, helices 7 and 8 span the length of the folded domain and form essentially one continuous helix with a kink in the middle. Helices 10-12 form an apparently stable C-terminal extension of the structural domain, and although other RGS proteins lack this structure, these elements are intimately associated with the rest of the structural framework by hydrophobic interactions. Members of the family bind to active G-alpha proteins, promoting GTP hydrolysis by the alpha subunit of heterotrimeric G proteins, thereby inactivating the G protein and rapidly switching off G protein-coupled receptor signalling pathways.