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TRPM5 is a voltage-modulated and Ca(2+)-activated monovalent selective cation channel

Thomas Hofmann1, Vladimir Chubanov, Thomas Gudermann

  • 1Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21215, USA.

Current Biology : CB
|July 5, 2003
PubMed

Insights

TRPM5 channels are calcium-activated, monovalent cation channels involved in taste signaling. These channels exhibit voltage modulation and rapid kinetics, distinguishing them from other TRP channels.

Area of Science:

  • Molecular Biology
  • Ion Channel Physiology
  • Sensory Neuroscience

Background:

  • Transient Receptor Potential Melastatin (TRPM) channels are crucial in cellular signaling.
  • TRPM5, a TRP channel, is implicated in taste receptor cells but its regulation remains unclear.
  • Understanding TRPM5 gating is vital for elucidating taste transduction pathways.

Purpose of the Study:

  • To elucidate the specific activation and gating mechanisms of the TRPM5 channel.
  • To characterize the biophysical properties of TRPM5, including its selectivity and conductance.
  • To investigate the role of calcium and voltage in TRPM5 channel function.

Main Methods:

  • Patch-clamp electrophysiology to record TRPM5 unitary conductance and channel activity.
  • Receptor stimulation assays coupled to phospholipase C activation.
  • Investigating the effects of intracellular calcium levels and membrane potential on TRPM5 gating.

Main Results:

  • TRPM5 functions as a monovalent-specific cation channel with a unitary conductance of 23 pS.
  • TRPM5 activity is dependent on phospholipase C activation and IP(3)-mediated calcium release.
  • TRPM5 exhibits voltage modulation and rapid activation/deactivation kinetics, unlike other mammalian TRP channels.
  • TRPM4b, a related channel, also shows voltage modulation but with slower kinetics.

Conclusions:

  • TRPM5 and TRPM4b are identified as the first voltage-modulated, calcium-activated, monovalent cation channels (VCAMs).
  • The unique properties of TRPM5, including voltage modulation and rapid kinetics, are well-suited for signaling in taste receptors and other excitable cells.
  • This study provides novel insights into the regulation and function of TRPM5 in cellular signaling pathways.

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