Molecular cloning and functional characterization of KCC3, a new K-Cl cotransporter

Joanne E. Race, Fadi N. Makhlouf, Paul J. Logue, Frederick H. Wilson, Philip B. Dunham, Eli J. Holtzman

Research output: Contribution to journalArticlepeer-review


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 ~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 NH2 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.

Original languageEnglish
Pages (from-to)C1210-C1219
JournalAmerican Journal of Physiology - Cell Physiology
Issue number6 46-6
StatePublished - 1999
Externally publishedYes


  • Cell volume regulation
  • HEK-293 cells
  • Inorganic ion cotransport


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