# VOLTAGE-SENSING MECHANISMS OF ION CHANNELS IN DYNAMIC LIPID MEMBRANES

> **NIH NIH R35** · SAINT LOUIS UNIVERSITY · 2024 · $378,750

## Abstract

PROJECT SUMMARY/ABSTRACT
 Ion channels in the voltage-gated ion channel (VGIC) superfamily play pivotal roles in virtually all
physiological processes. This proposal delves into essential constituents of this superfamily, focusing on
elucidating the mechanisms governing voltage sensing and electromechanical coupling of these proteins in
pathophysiological contexts. Our investigation focuses on discerning the regulatory interplay between the
voltage-sensing domain (VSD) of VGICs and the lipid-ordered membrane domain (OMD) enriched with
cholesterol. Recent findings from our laboratory have unraveled the significant influence of OMD on modulating
membrane excitability in somatosensory dorsal root ganglion (DRG) neurons. A reduction in OMD dimensions,
leading to augmented native ionic currents of pacemaker hyperpolarization-activated cyclic nucleotide-gated
(HCN) channels, emerges as a contributing factor in neuropathic pain and inflammatory pain. These distinct lipid
nanodomains exercise direct control over the voltage sensor of HCN channels, consequently influencing channel
opening. This aspect of HCN channel regulation, integral to neuronal excitability and cardiac pacemaking,
necessitates in-depth investigation. Our biophysical approach employs patch-clamp fluorometry (PCF) combined
with fluorescence lifetime imaging microscopy (FLIM) to measure voltage-sensor conformational dynamics within
native lipid environments. Leveraging genetic-code expansion featuring noncanonical amino acids and bio-
orthogonal fluorescence labeling through click chemistry enables site-specific labeling and facilitates Förster
resonance energy transfer (FRET) measurements. Furthermore, our approach includes an improved transition
metal FRET (tmFRET) technique in conjunction with phasor plot FLIM, with the primary goal of investigating the
potential intermediate states of VGIC voltage sensors. By successfully implementing this approach, we intend to
discern the influence of OMD localization, lipid composition, and disease-associated mutations on these
intermediate voltage sensor states. This extensive investigation holds the promise of significantly deepening our
understanding of the voltage-sensing mechanism of VGIC in physiological processes.

## Key facts

- **NIH application ID:** 10937298
- **Project number:** 1R35GM154778-01
- **Recipient organization:** SAINT LOUIS UNIVERSITY
- **Principal Investigator:** Gucan Dai
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $378,750
- **Award type:** 1
- **Project period:** 2024-07-15 → 2029-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10937298

## Citation

> US National Institutes of Health, RePORTER application 10937298, VOLTAGE-SENSING MECHANISMS OF ION CHANNELS IN DYNAMIC LIPID MEMBRANES (1R35GM154778-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10937298. Licensed CC0.

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