title: The rat Na+-sulfate cotransporter rNaS2: functional characterization, tissue distribution, and gene (slc13a4) structure.
abstract: Inorganic sulfate is essential for numerous functions in mammalian physiology. In the present study, we characterized the functional properties of the rat Na+-sulfate cotransporter NaS2 (rNaS2), determined its tissue distribution, and identified its gene (slc13a4) structure. Expression of rNaS2 protein in Xenopus oocytes led to a Na+-dependent transport of sulfate that was inhibited by phosphate, thiosulfate, tungstate, selenate, oxalate, and molybdate, but not by citrate, succinate, or DIDS. Transport kinetics of rNaS2 determined a K(M) for sulfate of 1.26 mM. Na+ kinetics determined a Hill coefficient of n=3.0+/-0.7, suggesting a Na+:SO4 (2-) stoichiometry of 3:1. rNaS2 mRNA was highly expressed in placenta, with lower levels found in the brain and liver. slc13a4 maps to rat chromosome 4 and contains 17 exons, spanning over 46 kb in length. This gene produces two alternatively spliced transcripts, of which the transcript lacking exon 2 is the most abundant form. Its 5' flanking region contains CAAT- and GC-box motifs and a number of putative transcription factor binding sites, including GATA-1, SP1, and AP-2 consensus sequences. This is the first study to characterize rNaS2 transport kinetics, define its tissue distribution, and resolve its gene (slc13a4) structure and 5' flanking region.
authors.affiliation: School of Biomedical Sciences, University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dawson
authors.forename: Katrina J
authors.initials: KJ
authors.lastname: Pirlo
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Steane
authors.forename: Kim A
authors.initials: KA
authors.lastname: Nguyen
authors.forename: Karl
authors.initials: K
authors.lastname: Kunzelmann
authors.forename: Yu Ju
authors.initials: YJ
authors.lastname: Chien
authors.forename: Daniel
authors.initials: D
authors.lastname: Markovich
mesh_terms: D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D005260:Female; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000502:physiology*; D010920:Placenta / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000076988:Sulfate Transporters; D027981:Symporters / Q000235:genetics / Q000502:physiology*; D014018:Tissue Distribution
chemical_list: D029363:Organic Anion Transporters, Sodium-Dependent; C505421:Slc13a4 protein, rat; D000076988:Sulfate Transporters; D027981:Symporters