title: Molecular and phylogenetic characterization of a novel putative membrane transporter (SLC10A7), conserved in vertebrates and bacteria.
abstract: The 'Solute Carrier Family SLC10' consists of six annotated members in humans, comprising two bile acid carriers (SLC10A1 and SLC10A2), one steroid sulfate transporter (SLC10A6), and three orphan carriers (SLC10A3 to SLC10A5). In this study we report molecular characterization and expression analysis of a novel member of the SLC10 family, SLC10A7, previously known as C4orf13. SLC10A7 proteins consist of 340-343 amino acids in humans, mice, rats, and frogs and show an overall amino acid sequence identity of >85%. SLC10A7 genes comprise 12 coding exons and show broad tissue expression pattern. When expressed in Xenopus laevis oocytes and HEK293 cells, SLC10A7 was detected in the plasma membrane but revealed no transport activity for bile acids and steroid sulfates. By immunofluorescence analysis of dual hemagglutinin (HA)- and FLAG-labeled SLC10A7 proteins in HEK293 cells, we established a topology of 10 transmembrane domains with an intracellular cis orientation of the N-terminal and C-terminal ends. This topology pattern is clearly different from the seven-transmembrane domain topology of the other SLC10 members but similar to hitherto uncharacterized non-vertebrate SLC10A7-related proteins. In contrast to the established SLC10 members, which are restricted to the taxonomic branch of vertebrates, SLC10A7-related proteins exist also in yeasts, plants, and bacteria, making SLC10A7 taxonomically the most widespread member of this carrier family. Vertebrate and bacterial SLC10A7 proteins exhibit >20% sequence identity, which is higher than the sequence identity of SLC10A7 to any other member of the SLC10 carrier family.
authors.affiliation: Institute of Pharmacology and Toxicology, Justus Liebig University of Giessen, Frankfurter Strasse 107, D-35392 Giessen, Germany.
authors.forename: José R
authors.initials: JR
authors.lastname: Godoy
authors.forename: Carla
authors.initials: C
authors.lastname: Fernandes
authors.forename: Barbara
authors.initials: B
authors.lastname: Döring
authors.forename: Knut
authors.initials: K
authors.lastname: Beuerlein
authors.forename: Ernst
authors.initials: E
authors.lastname: Petzinger
authors.forename: Joachim
authors.initials: J
authors.lastname: Geyer
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000235:genetics*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005091:Exons / Q000235:genetics; D016678:Genome; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes; D029363:Organic Anion Transporters, Sodium-Dependent / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D027981:Symporters / Q000378:metabolism; D014714:Vertebrates / Q000235:genetics*; D014981:Xenopus
chemical_list: D029363:Organic Anion Transporters, Sodium-Dependent; D011993:Recombinant Fusion Proteins; D027981:Symporters; C071908:sodium-bile acid cotransporter