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-alpha subfamily 1 members, with the order G(i)a3 > G(i)a1 > G(o)a >> G(z)a/G(i)a2. Activity on G(z)-alpha is inhibited by phosphorylation and palmitoylation of the G-protein. Interacts with GIPC PDZ domain. Highest expression in lung. Placenta, liver and heart also express high levels of GAIP. Fatty acylated. Heavily palmitoylated in the cysteine string motif. Phosphorylated, mainly on serine residues.