title: A novel family of ancient vertebrate odorant receptors.
abstract: Vertebrate odorant receptor (OR) genes have been isolated and characterized in several taxa, including bony fish and mammals. However, the search for more ancient vertebrate OR genes has been unsuccessful to date, indicating that these ancient genes share little sequence identity with previously isolated ORs. The lamprey (Lampetra fluviatilis) olfactory epithelium does not appear to express any of the modern vertebrate ORs previously identified in bony fish and mammals. We have isolated and characterized an ancient family of vertebrate membrane receptors from the olfactory epithelium of the lamprey. Sequence analysis reveals similarities with other Class A (rhodopsin-like) G protein-coupled receptors such as serotonin, dopamine, and histamine receptors, but the expression patterns of members of the new family, as well as certain conserved motifs, strongly suggest that the sequences encode ORs. Sequence similarity within the lamprey OR family is low, and Southern blot analysis suggests reduced-sized subfamilies. This novel vertebrate OR gene family, the most ancient isolated to date, is proposed to be involved in the detection of water-borne molecules in jawless fishes. Lamprey OR genes therefore represent a new level of diversity within the vertebrate OR gene family, but also provide clues as to how vertebrate ORs might have emerged.
authors.affiliation: Department of Cell and Molecular Biology, Umeå University, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Berghard
authors.forename: L
authors.initials: L
authors.lastname: Dryer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D007798:Lampreys / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009831:Olfactory Mucosa / Q000378:metabolism; D010802:Phylogeny; D018035:Receptors, Odorant / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D018035:Receptors, Odorant