title: Membrane topology of the Drosophila OR83b odorant receptor.
abstract: By analogy to mammals, odorant receptors (ORs) in insects, such as Drosophila melanogaster, have long been thought to belong to the G-protein coupled receptor (GPCR) superfamily. However, recent work has cast doubt on this assumption and has tentatively suggested an inverted topology compared to the canonical N(out) - C(in) 7 transmembrane (TM) GPCR topology, at least for some Drosophila ORs. Here, we report a detailed topology mapping of the Drosophila OR83b receptor using engineered glycosylation sites as topology markers. Our results are inconsistent with a classical GPCR topology and show that OR83b has an intracellular N-terminus, an extracellular C-terminus, and 7TM helices.
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Svante Arrheniusv 12, SE-106 91, Stockholm, Sweden.
authors.forename: Carolina
authors.initials: C
authors.lastname: Lundin
authors.forename: Lukas
authors.initials: L
authors.lastname: Käll
authors.forename: Scott A
authors.initials: SA
authors.lastname: Kreher
authors.forename: Katja
authors.initials: K
authors.lastname: Kapp
authors.forename: Erik L
authors.initials: EL
authors.lastname: Sonnhammer
authors.forename: John R
authors.initials: JR
authors.lastname: Carlson
authors.forename: Gunnar von
authors.initials: Gv
authors.lastname: Heijne
authors.forename: IngMarie
authors.initials: I
authors.lastname: Nilsson
mesh_terms: D000818:Animals; D015415:Biomarkers; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism*; D006031:Glycosylation; D008861:Microsomes / Q000378:metabolism; D008954:Models, Biological; D018035:Receptors, Odorant / Q000737:chemistry* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D029721:Drosophila Proteins; C492465:Orco protein, Drosophila; D018035:Receptors, Odorant