SBD, A NOVEL STRUCTURAL SUBUNIT OF THE DROSOPHILA NICOTINIC ACETYLCHOLINE-RECEPTOR, SHARES ITS GENOMIC LOCALIZATION WITH 2 ALPHA-SUBUNITS

Nicotinic acetylcholine receptors (nAChRs) display marked heterogeneity in both vertebrates and invertebrates. Here we describe the structure of a cDNA from Drosophila melanogaster which encodes a novel nAChR β-type subunit (SBD or β2). The deduced amino acid sequence of SBD displays remarkable similarity to the Drosophila α-subunits, ALS and SAD, while homology to the Drosophila β-subunit ARD is less pronounced. The temporal expression of sbd transcripts during Drosophila development is similar to that of other nAChR subunit mRNAs, with high levels being found during late embryonic and late pupal stages. In embryos, sbd and als transcripts are localized in the central nervous system. The sbd gene maps cytogenetically in proximity to the als and sad genes at position 96A of chromosome 3R, suggesting the existence of a nAChR gene cluster in invertebrates. © 1990.