title: Functional characterization of three novel tissue-specific anion exchangers SLC26A7, -A8, and -A9.
abstract: A second distinct family of anion exchangers, SLC26, in addition to the classical SLC4 (or anion exchanger) family, has recently been delineated. Particular interest in this gene family is stimulated by the fact that the SLC26A2, SLC26A3, and SLC26A4 genes have been recognized as the disease genes mutated in diastrophic dysplasia, congenital chloride diarrhea, and Pendred syndrome, respectively. We report the expansion of the SLC26 gene family by characterizing three novel tissue-specific members, named SLC26A7, SLC26A8, and SLC26A9, on chromosomes 8, 6, and 1, respectively. The SLC26A7-A9 proteins are structurally very similar at the amino acid level to the previous family members and show tissue-specific expression in kidney, testis, and lung, respectively. More detailed characterization by immunohistochemistry and/or in situ hybridization localized SLC26A7 to distal segments of nephrons, SLC26A8 to developing spermatocytes, and SLC26A9 to the lumenal side of the bronchiolar and alveolar epithelium of lung. Expression of SLC26A7-A9 proteins in Xenopus oocytes demonstrated chloride, sulfate, and oxalate transport activity, suggesting that they encode functional anion exchangers. The functional characterization of the novel tissue-specific members may provide new insights to anion transport physiology in different parts of body.
authors.affiliation: Department of Medical Genetics, Biomedicum Helsinki and Helsinki University Central Hospital, P. O. Box 63 (Haartmaninkatu 8), 00014 University of Helsinki, Helsinki, Finland.
authors.forename: Hannes
authors.initials: H
authors.lastname: Lohi
authors.forename: Minna
authors.initials: M
authors.lastname: Kujala
authors.forename: Siru
authors.initials: S
authors.lastname: Makela
authors.forename: Eero
authors.initials: E
authors.lastname: Lehtonen
authors.forename: Marjo
authors.initials: M
authors.lastname: Kestila
authors.forename: Ulpu
authors.initials: U
authors.lastname: Saarialho-Kere
authors.forename: Daniel
authors.initials: D
authors.lastname: Markovich
authors.forename: Juha
authors.initials: J
authors.lastname: Kere
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D027321:Anion Transport Proteins; D000838:Anions; D017920:Antiporters / Q000737:chemistry* / Q000235:genetics; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007438:Introns; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D000076988:Sulfate Transporters; D014018:Tissue Distribution; D014981:Xenopus
chemical_list: D027321:Anion Transport Proteins; D000838:Anions; D017920:Antiporters; D002352:Carrier Proteins; D018076:DNA, Complementary; C455626:SLC26A7 protein, human; C455627:SLC26A8 protein, human; C455628:SLC26A9 protein, human; D000076988:Sulfate Transporters