Abstract GTP stimulation of adenylyl cyclase from the dimorphic pathogenic fungus Candida albicans is greatly enhanced by preincubation of membrane proteins with cholera toxin, NAD and ATP. In the presence of [ 32P]NAD the toxin catalyzes the covalent incorporation of radioactivity into a menbrane protein of 40 kDa. Pertussis toxin catalyzes the transference of the radioactivity from [ 32P]NAD to a 32 kDa protein. Two major proteins of 40–42 and 30–32 kDa can also be recognized in Western blots by an anti G α-common antibody. The results support the idea that G proteins are part of the hormonesensory transduction chain of Candida [(1990) Biochem. Biophys. Res. Commun. 167. 1177-1183].