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Updated: Jun 4, 2025

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy
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Effects of TRPC1's Lysines on Heteromeric TRPC5-TRPC1 Channel Function

Isaac S Demaree1, Sanjay Kumar1,2, Kayla Tennessen3

  • 1Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.

Cells
|December 17, 2024
PubMed
Abstract

Insights

TRPC1 inhibits TRPC5 ion channel function through specific positively charged lysine residues in the pore lumen. This finding clarifies the mechanism of TRPC5/TRPC1 heteromer regulation and extracellular Mg2+ inhibition.

Area of Science:

  • Ion channel physiology
  • Molecular and cellular neuroscience
  • Cardiovascular research

Background:

  • Transient Receptor Potential Canonical (TRPC) proteins, including TRPC5, form plasma membrane cation channels crucial for nervous and cardiovascular systems.
  • TRPC5 channel activation increases neuronal excitability, while TRPC1 acts as an inhibitor through heteromerization, but the precise inhibitory mechanism remains unclear.

Purpose of the Study:

  • To investigate the role of subunit stoichiometry and specific charged residues in TRPC1's inhibitory function on TRPC5/TRPC1 heteromeric channels.
  • To elucidate the molecular basis for TRPC1-mediated inhibition of TRPC5 channel activity.

Main Methods:

  • Electrophysiological techniques were employed to assess TRPC5/TRPC1 heteromer function under varying subunit compositions.
  • Molecular dynamics simulations were performed to analyze the structural interactions within the TRPC5/TRPC1 channel pore.
  • Site-directed mutagenesis was used to substitute key lysine residues in TRPC1.

Main Results:

  • Increased TRPC1 expression in TRPC5/TRPC1 heteromers significantly reduced histamine-induced cation influx.
  • Molecular dynamics simulations identified two positively charged lysine residues in TRPC1 facing the heteromeric pore lumen.
  • Mutating these lysines diminished TRPC1's inhibitory effect, suggesting their role in regulating cation flow.
  • Extracellular Mg2+ was found to inhibit cation influx through TRPC5/TRPC1 channels.

Conclusions:

  • The inhibitory action of TRPC1 on TRPC5/TRPC1 heteromeric channel function is mediated by positively charged lysine residues located within the channel pore lumen.
  • These findings provide critical insights into the regulation of TRPC5/TRPC1 channel activity and potential therapeutic targets.
Keywords:
TRPC channelsTRPC1-TRPC5 heteromerscation channelselectrophysiologymolecular dynamics

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