A Unified Nomenclature System for the Insect Olfactory Coreceptor

Extract

We propose a revised nomenclature for the insect olfactory coreceptor variously named “Or83b,” “Or1,” “Or2,” and “Or7.” This gene appears to be functionally orthologous across all insects and serves as a chaperoning coreceptor for the odor- and pheromone-specific subunits of the insect olfactory receptor gene family (Krieger et al. 2003; Larsson et al. 2004; Pitts et al. 2004; Nakagawa et al. 2005; Benton et al. 2006). The insect odorant receptors (Ors) are atypical 7-transmembrane domain proteins that form ligand-gated ion channels by assembling a ligand-selective subunit with the olfactory coreceptor (Nakagawa et al. 2005; Sato et al. 2008; Wicher et al. 2008). The Or gene family appears to be an insect-specific adaptation (Robertson et al. 2003) as neither ligand-selective Ors nor the olfactory coreceptor have been identified in any noninsect genomes (Penalva-Arana et al. 2009).

Although the insect olfactory coreceptor appears to perform the same function in all insects, there is no consistency in nomenclature across species. The current nomenclature system with different names in different insect species is confusing, unnecessary, and negatively impacts our ability to communicate our work to nonspecialists. The confusion is compounded by ambiguity in gene names: Or2 and Or7 are not unique names but names that vary in function across species. For instance, Or2 in Bombyx mori refers to the olfactory coreceptor, whereas in Anopheles gambiae, Or2 refers to a 2-methylphenol receptor. Or7 is the coreceptor in Anopheles and Aedes but is an odor-specific receptor in various Lepidopteran species.