# Simultaneous single-molecule optical and electrical measurements of ion channel ligand binding and pore gating

> **NIH NIH R03** · UNIVERSITY OF TEXAS AT AUSTIN · 2022 · $76,033

## Abstract

PROJECT SUMMARY
Ligand-gated ion channels (LGICs) are molecular sensors that convert the chemical energy of ligand binding to
electrical impulses via ion flux through the channel pore. LGICs are essential for synaptic transmission
throughout the nervous system as well as cellular signaling in many other fundamental physiological processes
such as vision, olfaction, motor control and heart rate to name just a few. They are also major drug targets as
modulating channel behavior can be used to counteract a wide range of afflictions such as anxiety, addiction,
pain, muscle impairment, etc. Gating (opening/closing) of the channel pore is initiated upon binding of ligands,
often to multiple sites in distinct subunits or domains. Despite significant progress in understanding the 3-
dimensional structure of LGICs, there remains a critical gap in our understanding of how these domains
participate to shape the sequence of events by which chemical binding energy is transduced to gating of the ion
pore. A major barrier to bridging this gap is that the single-molecule methods needed to resolve the stochastic
binding and gating events only report on either the binding stimulus or the gating response, but not both as
required to understand the full stimulus-response pathway. To overcome this barrier, I will use an innovative
combination of micro-mirror total internal reflection fluorescence (mmTIRF) single-molecule imaging to optically
track individual binding events for a fluorescently labeled ligand while simultaneously recording ion conduction
through single channels in excised membrane patches with conventional patch clamp techniques. The objective
of this proposal is to establish the feasibility of this combined approach for activation of cyclic nucleotide gated
(CNG) channels critical for visual and olfactory sensation. The rationale is that the combination of mmTIRF and
single-channel recording will enable direct experimental correlation between distinct binding events at multiple
domains and the electrical gating response. Completion of this objective will 1) establish a facile approach for
probing the full stimulus-response pathway in LGICs at single-molecule resolution, and 2) determine the degree
to which energy from binding one or two cyclic nucleotides is transduced to opening of the pore gate. The
proposed research is significant because it will enable studies that probe the dynamic sequence of events
governing the transduction of chemical binding energy in multiple domains to gating of the ion pore, a process
which in many cases is only poorly understood. The approach developed in this proposal will be invaluable to
understanding the dynamic events by which ligands drive channel activity and which connect the dots between
static structural snapshots, and thereby will constitute a major step forward for the ion channel field. Furthermore,
it will have direct bearing on understanding the mechanisms of drugs that modulate channel behavior, which wil...

## Key facts

- **NIH application ID:** 10575611
- **Project number:** 1R03NS130369-01
- **Recipient organization:** UNIVERSITY OF TEXAS AT AUSTIN
- **Principal Investigator:** Marcel Paz Goldschen-Ohm
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $76,033
- **Award type:** 1
- **Project period:** 2022-09-01 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10575611

## Citation

> US National Institutes of Health, RePORTER application 10575611, Simultaneous single-molecule optical and electrical measurements of ion channel ligand binding and pore gating (1R03NS130369-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10575611. Licensed CC0.

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