title: Molecular cloning and expression of a cyclic AMP-activated chloride conductance regulator: a novel ATP-binding cassette transporter.
abstract: Cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-regulated, cAMP-activated chloride channel located in the apical membrane of many epithelial secretory cells. Here we report cloning of a cAMP-activated epithelial basolateral chloride conductance regulator (EBCR) that appears to be a basolateral CFTR counterpart. This novel chloride channel or regulator shows 49% identity with multidrug resistance-associated protein (MRP) and 29% identity with CFTR. On expression in Xenopus oocytes, EBCR confers a cAMP-activated chloride conductance that is inhibited by the chloride channel blockers niflumic acid, 5-nitro-2-(3-phenylpropylamine)benzoic acid, and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. Northern blot analysis reveals high expression in small intestine, kidney, and liver. In kidney, immunohistochemistry shows a conspicuous basolateral localization mainly in the thick ascending limb of Henle's loop, distal convoluted tubules and to a lesser extent connecting tubules. These data suggest that in the kidney EBCR is involved in hormone-regulated chloride reabsorption.
authors.affiliation: Department of Cell Physiology, University of Nijmegen, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: van Kuijck
authors.forename: R A
authors.initials: RA
authors.lastname: van Aubel
authors.forename: A E
authors.initials: AE
authors.lastname: Busch
authors.forename: F
authors.initials: F
authors.lastname: Lang
authors.forename: F G
authors.initials: FG
authors.lastname: Russel
authors.forename: R J
authors.initials: RJ
authors.lastname: Bindels
authors.forename: C H
authors.initials: CH
authors.lastname: van Os
authors.forename: P M
authors.initials: PM
authors.lastname: Deen
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000737:chemistry / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002462:Cell Membrane / Q000502:physiology; D018118:Chloride Channels / Q000502:physiology*; D003001:Cloning, Molecular; D005576:Colforsin / Q000494:pharmacology; D004848:Epithelium / Q000502:physiology; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000502:physiology; D007668:Kidney / Q000502:physiology*; D008099:Liver / Q000502:physiology; D008564:Membrane Potentials; D008961:Models, Structural; D008969:Molecular Sequence Data; D009544:Niflumic Acid / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D009928:Organ Specificity; D018408:Patch-Clamp Techniques; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D018118:Chloride Channels; D011994:Recombinant Proteins; C099627:mrp2 protein, Oryctolagus cuniculus; D005576:Colforsin; D009544:Niflumic Acid; D000255:Adenosine Triphosphate; D015056:1-Methyl-3-isobutylxanthine