Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. This subunit is involved in cAMP regulation and morphogenesis. It is essential for dimorphic switching in haploid cells. G proteins are composed of 3 units; alpha, beta and gamma. The alpha chain contains the guanine nucleotide binding site. Belongs to the G-alpha family.