Abstract
In mammals, the alpha subunit of the stimulatory guanine nucleotide-binding protein (Gs alpha) functions to couple a variety of extracellular membrane receptors to adenylate cyclase. Activation of Gs alpha results in the stimulation of adenylate cyclase and an increase in the second messenger cAMP. A 1.7-kilobase cDNA has been identified and characterized from Drosophila that codes for a protein 71% identical to bovine Gs alpha. The similarity is most striking in the regions thought to be responsible for the interactions with receptors and effectors, suggesting that the basic components of this signal-transduction pathway have been conserved through evolution. RNA blot hybridization and DNA sequence analysis suggest that a single transcript, expressed predominantly in the head, is present in Drosophila. In situ hybridization studies indicate that the Drosophila Gs alpha transcript is localized primarily in the cells of the central nervous system and in the eyes.
