Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. Stimulated by RGS14. The G(o) protein function is not clear. G proteins are composed of 3 units; alpha, beta and gamma. The alpha chain contains the guanine nucleotide binding site. Interacts with RGS14. Histaminylated at Gln-205 residues by TGM2. Belongs to the G-alpha family. G(i/o/t/z) subfamily.