A proton current associated with sour taste: distribution and functional properties

FASEB J. 2015 Jul;29(7):3014-26. doi: 10.1096/fj.14-265694. Epub 2015 Apr 9.


Sour taste is detected by taste receptor cells that respond to acids through yet poorly understood mechanisms. The cells that detect sour express the protein PKD2L1, which is not the sour receptor but nonetheless serves as a useful marker for sour cells. By use of mice in which the PKD2L1 promoter drives expression of yellow fluorescent protein, we previously reported that sour taste cells from circumvallate papillae in the posterior tongue express a proton current. To establish a correlation between this current and sour transduction, we examined its distribution by patch-clamp recording. We find that the current is present in PKD2L1-expressing taste cells from mouse circumvallate, foliate, and fungiform papillae but not in a variety of other cells, including spinal cord neurons that express PKD2L1. We describe biophysical properties of the current, including pH-dependent Zn(2+) inhibition, lack of voltage-dependent gating, and activation at modest pH values (6.5) that elicit action potentials in isolated cells. Consistent with a channel that is constitutively open, the cytosol of sour taste cells is acidified. These data define a functional signature for the taste cell proton current and indicate that its expression is mostly restricted to the subset of taste cells that detect sour.

Keywords: PKD2L1; acid; ion channel; pH; sensory transduction.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials
  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Biophysical Phenomena
  • Calcium Channels / genetics
  • Calcium Channels / physiology*
  • Cell Line
  • HEK293 Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Mice
  • Mice, Transgenic
  • Promoter Regions, Genetic
  • Protons
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / physiology*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Taste / genetics
  • Taste / physiology*
  • Taste Buds / cytology*
  • Taste Buds / physiology*


  • Bacterial Proteins
  • Calcium Channels
  • Luminescent Proteins
  • PKD2L1 protein, human
  • Pkd2l1 protein, mouse
  • Protons
  • Receptors, Cell Surface
  • Recombinant Proteins
  • yellow fluorescent protein, Bacteria