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Involvement of pore helix in voltage-dependent inactivation of TRPM5 channel

Kunitoshi Uchida1,2, Tomo Kita1,3, Mitsutoki Hatta1

  • 1Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Fukuoka, 814-0193, Japan.

Heliyon
|February 8, 2021
PubMed

Insights

The transient receptor potential melastatin 5 (TRPM5) channel

Area of Science:

  • Molecular Biology
  • Ion Channel Physiology
  • Neuroscience

Background:

  • Transient receptor potential melastatin 5 (TRPM5) is a Ca2+-activated cation channel.
  • TRPM5 is expressed in taste cells, pancreas, brainstem, and olfactory epithelium.
  • TRPM5 plays a role in controlling membrane potentials.

Purpose of the Study:

  • To investigate the role of the TRPM5 pore helix in voltage-dependent inactivation.
  • To identify specific residues within the pore helix that influence TRPM5 gating.

Main Methods:

  • Whole-cell patch-clamp recordings were used to assess TRPM5 channel activity.
  • Site-directed mutagenesis was employed to substitute specific amino acids in the TRPM5 pore helix.
  • The time constant of voltage-dependent inactivation was measured under varying intracellular Ca2+ concentrations.

Main Results:

  • TRPM5 exhibited voltage-dependent inactivation at negative membrane potentials.
  • Intracellular Ca2+ concentration (100-500 nM) did not affect the time constant of inactivation.
  • Alanine substitutions at Y913 and I916 increased the inactivation time constant.
  • Glycine substitutions at L901, Y913, Q915, and I916 reduced voltage-dependent inactivation.

Conclusions:

  • The pore helix of TRPM5 is crucial for voltage-dependent inactivation.
  • Specific residues within the outer pore loop of TRPM5 modulate its inactivation kinetics.
Keywords:
CalciumInactivationPore helixTRPM5Voltage dependence

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