Expression of chloride channel, ClC-5, and its role in receptor-mediated endocytosis of albumin in OK cells

Biochem Biophys Res Commun. 2001 Mar 23;282(1):212-8. doi: 10.1006/bbrc.2001.4557.


By using Western blot and RT-PCR analyses, the expression of ClC-5, a member of the ClC family of voltage-gated chloride channels, and its mRNA was detected in OK cells. The effect of chloride channel inhibitors on receptor-mediated endocytosis of albumin was examined in OK cells and compared to that of vacuolar H(+)-ATPase inhibitors. Accumulation of fluorescein-isothiocyanate (FITC)-albumin, a receptor-mediated endocytosis marker, was inhibited by 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), a chloride channel inhibitor, in a concentration-dependent fashion. In contrast, uptake of FITC-inulin, a fluid-phase endocytosis marker, was not affected by NPPB. Other chloride channel inhibitors, 4,4'-diisothiocyanatostilbene-2-2'-disulfonic acid and diphenylamine-2-carboxylic acid, also inhibited FITC-albumin uptake. NPPB, as well as a vacuolar H(+)-ATPase inhibitor bafilomycin A(1), caused a decrease in the affinity and in the maximal velocity of FITC-albumin uptake. These results suggest that chloride channel, most likely ClC-5, plays an important role in the receptor-mediated endocytosis of albumin in OK cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Albumins / metabolism*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Chloride Channels / genetics*
  • Chloride Channels / physiology
  • Endocytosis / physiology*
  • Fluorescein-5-isothiocyanate
  • Kinetics
  • Molecular Sequence Data
  • Opossums
  • Receptors, Cell Surface / physiology*
  • Reverse Transcriptase Polymerase Chain Reaction


  • Albumins
  • CLC-5 chloride channel
  • Chloride Channels
  • Receptors, Cell Surface
  • Fluorescein-5-isothiocyanate