Comparison of odorant specificity of two human olfactory receptors from different phylogenetic classes and evidence for antagonism.
Humans are able to detect and discriminate myriads of odorants using only several hundred olfactory receptors (ORs) classified in two major phylogenetic classes representing ORs from aquatic (class I) and terrestrial animals (class II). Olfactory perception results in a combinatorial code, in which one OR recognizes multiple odorants and different odorants are recognized by different combinations of ORs. Moreover, recent data suggest that odorants could also behave as antagonists for other ORs, thus making the combinatorial coding more complex. Here we describe the odorant repertoires of two human ORs belonging to class I and class II, respectively. For this purpose, we set up an assay based on calcium imaging in which 100 odorants were screened using air-phase odorant stimulation at physiological doses. We showed that the human class I OR52D1 is functional, exhibiting a narrow repertoire related to that of its orthologous murine OR, demonstrating than this human class I OR is not an evolutionary relic. The class II OR1G1 was revealed to be broadly tuned towards odorants of 9-10 carbon chain length, with diverse functional groups. The existence of antagonist odorants for the class II OR was also demonstrated. They are structurally related to the agonists, with shorter carbon chain length.
Sanz
Guenhaël
G
Biochimie de l'Olfaction et de la Gustation, Neurobiologie de l'Olfaction et de la Prise Alimentaire, INRA, Domaine de Vilvert, Bâtiment 526, F 78352 Jouy-en-Josas Cedex, France.
Schlegel
Claire
C
Pernollet
Jean-Claude
JC
Briand
Loïc
L
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000502:physiology; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009812:Odorants / Q000032:analysis*; D010802:Phylogeny; D018035:Receptors, Odorant / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000235:genetics; D012903:Smell
D018035:Receptors, Odorant; D019204:GTP-Binding Proteins