Functional properties of Drosophila dopamine D1-receptors are not altered by the size of the N-terminus

Molecular cloning revealed the existance of at least five pharmacologically different dopamine receptors in vertebrates. Functionally, dopamine receptors either activate (D1-type), inhibit or do not interact with adenylate cyclase (D2-type). A recently cloned dopamine receptor from Drosophila melanogaster shares many structural and functional properties with vertebrate D1-type receptors but the pharmacological properties are very different. In contrast to most aminergic receptors, DmDop1 contains a long N-terminal extension. Here we describe a deletion-mutagenesis approach to study whether the N-terminus of DmDop1 participates in receptor-ligand interactions. All mutants gave rise to functional receptors after heterologous expression in HEK 293 cells. The pharmacological properties, however, remained unchanged. A comparison of DNA and deduced amino acid sequences revealed that some Drosophila strains express a truncated version of the DmDop1 receptor. (C) 1996 Academic Press, Inc.