Molecular cloning and transmembrane structure of hCLCA2 from human lung, trachea, and mammary gland

Academic Article


  • The CLCA family of Ca -activated Cl channels has recently been discovered, with an increasing number of closely related members isolated from different species. Here we report the cloning of the second human homolog, hCLCA2, from a human lung cDNA library. Northern blot and RT-PCR analyses revealed additional expression in trachea and mammary gland. A primary translation product of 120 kDa was cleaved into two cell surface- associated glycoproteins of 86 and 34 kDa in transfected HEK-293 cells, hCLCA2 is the first CLCA homolog for which the transmembrane structure has been systematically studied. Glycosylation site scanning and protease protection assays revealed five transmembrane domains with a large, cysteine- rich, amino-terminal extracellular domain. Whole cell patch-clamp recordings of hCLCA2-transfected HEK-293 cells detected a slightly outwardly rectifying anion conductance that was increased in the presence of the Ca ionophore ionomycin and inhibited by DIDS, dithiothreitol, niflumic acid, and tamoxifen. Expression in human trachea and lung suggests that hCLCA2 may play a role in the complex pathogenesis of cystic fibrosis. 2+ - 2+
  • Digital Object Identifier (doi)

    Author List

  • Gruber AD; Schreur KD; Ji HL; Fuller CM; Pauli BU
  • Volume

  • 276
  • Issue

  • 6 45-6