AGONIST-SPECIFIC COUPLING OF A CLONED DROSOPHILA OCTOPAMINE TYRAMINE RECEPTOR TO MULTIPLE 2ND MESSENGER SYSTEMS

A cloned seven transmembrane-spanning Drosophila octopamine/tyramine r eceptor, permanently expressed in a Chinese hamster ovary cell line, b oth inhibits adenylate cyclase activity and leads to the elevation of intracellular Ca2+ levels by separate G-protein-coupled pathways. Agon ists of this receptor (octopamine and tyramine), differing by only a s ingle hydroxyl group in their side chain, may be capable of differenti ally coupling it to different second messenger systems. Thus, a single receptor may have a different pharmacological profile depending on wh ich second messenger system is used to assay its efficacy.