title: Molecular cloning and functional characterization of KCC3, a new K-Cl cotransporter.
abstract: We isolated and characterized a novel K-Cl cotransporter, KCC3, from human placenta. The deduced protein contains 1,150 amino acids. KCC3 shares 75-76% identity at the amino acid level with human, pig, rat, and rabbit KCC1 and 67% identity with rat KCC2. KCC3 is 40 and 33% identical to two Caenorhabditis elegans K-Cl cotransporters and approximately 20% identical to other members of the cation-chloride cotransporter family (CCC), two Na-K-Cl cotransporters (NKCC1, NKCC2), and the Na-Cl cotransporter (NCC). Hydropathy analysis indicates a typical KCC topology with 12 transmembrane domains, a large extracellular loop between transmembrane domains 5 and 6 (unique to KCCs), and large NH(2) and COOH termini. KCC3 is predominantly expressed in kidney, heart, and brain, and is also expressed in skeletal muscle, placenta, lung, liver, and pancreas. KCC3 was localized to chromosome 15. KCC3 transiently expressed in human embryonic kidney (HEK)-293 cells fulfilled three criteria for increased expression of K-Cl cotransport: stimulation of cotransport by swelling, treatment with N-ethylmaleimide, or treatment with staurosporine.
authors.affiliation: Renal Division, Department of Medicine, State University of New York Health Science Center, Syracuse 13210, New York.
authors.forename: J E
authors.initials: JE
authors.lastname: Race
authors.forename: F N
authors.initials: FN
authors.lastname: Makhlouf
authors.forename: P J
authors.initials: PJ
authors.lastname: Logue
authors.forename: F H
authors.initials: FH
authors.lastname: Wilson
authors.forename: P B
authors.initials: PB
authors.lastname: Dunham
authors.forename: E J
authors.initials: EJ
authors.lastname: Holtzman
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D002460:Cell Line; D002713:Chlorine / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers; D005033:Ethylmaleimide / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000166:cytology; D008969:Molecular Sequence Data; D009995:Osmosis; D010802:Phylogeny; D010920:Placenta / Q000737:chemistry*; D011188:Potassium / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D027981:Symporters; D014162:Transfection; D000096922:K Cl- Cotransporters
chemical_list: D002352:Carrier Proteins; D002713:Chlorine; D017931:DNA Primers; D005033:Ethylmaleimide; D011188:Potassium; D013439:Sulfhydryl Reagents; D027981:Symporters; C119650:SLC12A6 protein, human; D000096922:K Cl- Cotransporters; C492281:Slc12a6 protein, rat