Identification and functional characterization of a voltage-gated chloride channel and its novel splice variant in taste bud cells

J Biol Chem. 2005 Oct 28;280(43):36150-7. doi: 10.1074/jbc.M507706200. Epub 2005 Aug 29.

Abstract

Taste bud cells are epithelial cells with neuronal properties. Voltage-dependent ion channels have been physiologically described in these cells. Here, we report the molecular identification and functional characterization of a voltage-gated chloride channel (ClC-4) and its novel splice variant (ClC-4A) from taste bud cells. ClC-4A skipped an exon near its 5'-end, incurring the loss of 60 amino acids at the N terminus. In situ hybridization and immunohistochemistry localized these two channels' transcripts and proteins to a subset of taste bud cells. Electrophysiological recordings of the heterologously expressed channels in Xenopus oocytes showed that ClC-4 and ClC-4A have opposite sensitivity to pH and unique ion selectivity. The chloride channel blockers niflumic acid and 5-nitro-2-(3-phenylpropylamino)benzoic acid had a slight or no inhibitory effect on the conductance of ClC-4, but both blockers inhibited ClC-4A, suggesting that ClC-4A is a candidate channel for an acid-induced 5-nitro-2-(3-phenylpropylamino)benzoic acid-sensitive current. Furthermore, these two channels may play a role in bitter-, sweet-, and umami-mediated taste transmission by regulating transmitter uptake into synaptic vesicles.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing*
  • Angiogenesis Inhibitors / pharmacology
  • Animals
  • Chloride Channels / genetics*
  • Chloride Channels / physiology
  • Cyclooxygenase Inhibitors / pharmacology
  • DNA, Complementary / metabolism
  • Electrophysiology
  • Exons
  • Humans
  • Hydrogen-Ion Concentration
  • Immunohistochemistry
  • In Situ Hybridization
  • Ions
  • Mice
  • Molecular Sequence Data
  • Niflumic Acid / metabolism
  • Niflumic Acid / pharmacology
  • Nitrobenzoates / pharmacology
  • Nucleic Acid Hybridization
  • Oocytes / metabolism
  • Protein Structure, Tertiary
  • RNA, Messenger / metabolism
  • Synaptic Vesicles / metabolism
  • Taste Buds / pathology*
  • Xenopus

Substances

  • Angiogenesis Inhibitors
  • CLC-5 chloride channel
  • CLCA4 protein, human
  • Chloride Channels
  • Cyclooxygenase Inhibitors
  • DNA, Complementary
  • Ions
  • Nitrobenzoates
  • RNA, Messenger
  • 5-nitro-2-(3-phenylpropylamino)benzoic acid
  • Niflumic Acid

Associated data

  • GENBANK/DQ186662