RGS10 inhibits signal transduction by increasing the GTPASE activity of G protein alpha subunits thereby driving them into their inactive GDP-bound form. It associates specifically with the activated forms of the G protein subunits G(I)-ALPHA and G(Z)- alpha but fails to interact with the structurally and functionally distinct G(S)-alpha subunit. Activity on G(Z)-alpha is inhibited by palmitoylation of the G-protein.