Insect olfactory receptors (also known as odorant receptors, ORs) are expressed in the cell membranes of the olfactory sensory neurons of insects. Similarly to mammalian olfactory receptors, in insects each olfactory sensory neuron expresses one type of OR, allowing the specific detection of a volatile chemical.[1]

In contrast to vertebrate ORs, which are seven transmembrane G protein coupled receptors (GPCRs), insect ORs are part of an unrelated group of ligand-gated ion channels.[2] Like GPCRs, insect ORs are transmembrane proteins with seven transmembrane helices, but with a reversed topology, with an intracellular N-terminus and an extracellular C-terminus.[3] Differently to mammalian ORs, insect ORs form a heteromer with a fixed monomer, Orco, and a variable OR monomer, which confers the odour specificity.[4][5]

The number of ORs in different species of insects is extremely variable ranging from as few as 8 in the damselfly,[6] to 60 in the fruit fly Drosophila melanogaster,[7] even to more than 500 in some ant species, reflecting the variability in odorant perception requirements associated to different lifestyles and social interactions.[8]

Insect ORs are investigated as targets for pest control given the possibility of altering the behaviour of insects by activating particular ORs with natural or optimized chemicals.[9]

References

  1. ↑ Kaupp UB (March 2010). "Olfactory signalling in vertebrates and insects: differences and commonalities". Nat. Rev. Neurosci. 11 (3): 188–200. doi:10.1038/nrn2789. hdl:11858/00-001M-0000-0028-6203-9. PMID 20145624. S2CID 1423273.
  2. ↑ Robertson, Hugh M. (2019-01-07). "Molecular Evolution of the Major Arthropod Chemoreceptor Gene Families". Annual Review of Entomology. 64 (1): 227–242. doi:10.1146/annurev-ento-020117-043322. ISSN 0066-4170.
  3. ↑ Katritch V, Cherezov V, Stevens RC (2013). "Structure-function of the G protein-coupled receptor superfamily". Annu. Rev. Pharmacol. Toxicol. 53: 531–56. doi:10.1146/annurev-pharmtox-032112-135923. PMC 3540149. PMID 23140243.
  4. ↑ Wicher D, Schäfer R, Bauernfeind R, Stensmyr MC, Heller R, Heinemann SH, Hansson BS (April 2008). "Drosophila odorant receptors are both ligand-gated and cyclic-nucleotide-activated cation channels". Nature. 452 (7190): 1007–11. Bibcode:2008Natur.452.1007W. doi:10.1038/nature06861. PMID 18408711. S2CID 4418144.
  5. ↑ Sato K, Pellegrino M, Nakagawa T, Nakagawa T, Vosshall LB, Touhara K (April 2008). "Insect olfactory receptors are heteromeric ligand-gated ion channels". Nature. 452 (7190): 1002–6. Bibcode:2008Natur.452.1002S. doi:10.1038/nature06850. PMID 18408712. S2CID 4413766.
  6. ↑ Ioannidis P, Simao FA, Waterhouse RM, Manni M, Seppey M, Robertson HM, Misof B, Niehuis O, Zdobnov EM (February 2017). "Genomic Features of the Damselfly Calopteryx splendens Representing a Sister Clade to Most Insect Orders". Genome Biol Evol. 9 (2): 415–430. doi:10.1093/gbe/evx006. PMC 5381652. PMID 28137743.
  7. ↑ Clark AG, Eisen MB, Smith DR, Bergman CM, Oliver B, Markow TA, Kaufman TC, Kellis M, Gelbart W, et al. (November 2007). "Evolution of genes and genomes on the Drosophila phylogeny". Nature. 450 (7167): 203–18. Bibcode:2007Natur.450..203C. doi:10.1038/nature06341. PMID 17994087. S2CID 2416812.
  8. ↑ Hansson BS, Stensmyr MC (December 2011). "Evolution of insect olfaction". Neuron. 72 (5): 698–711. doi:10.1016/j.neuron.2011.11.003. PMID 22153368.
  9. ↑ Venthur H, Zhou JJ (2018). "Odorant Receptors and Odorant-Binding Proteins as Insect Pest Control Targets: A Comparative Analysis". Front Physiol. 9: 1163. doi:10.3389/fphys.2018.01163. PMC 6117247. PMID 30197600.
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