# Structural energetics of voltage- and ligand-dependent gating in ion channels

> **NIH NIH R35** · UNIVERSITY OF WASHINGTON · 2024 · $404,300

## Abstract

Abstract
Ion channels are exquisite molecular machines that regulate the flow of ions across cell
membranes in response to stimuli such as voltage and small molecule ligands (e.g.
second messengers, and neurotransmitters). They underlie all electrical excitability in
the brain and heart, and defects in ion channels are responsible for many human
disorders. Despite decades of experiments and many high-resolution molecular
structures, we still do not know, for any channel, the mechanisms for voltage- or ligand-
dependent gating. The missing ingredient seems to be conformational energetics. The
energetics of the different channel conformations governs the time course, voltage-
dependence, and ligand-dependence of opening of the channel pore, and ultimately
electrical excitability of the cell. In this proposal we will determine the mechanisms of
voltage-dependent gating and ligand-dependent gating and fill important gaps in our
understanding of ion channel biology. We will focus on the cyclic nucleotide-binding
domain (CNBD) family of ion channels, which are structurally related, but functionally
diverse. Whereas some CNBD channels are activated by depolarization, others are
activated by hyperpolarization, and some members are activated by cAMP yet others
are activated by cGMP. We will leverage breakthrough FRET methods we developed for
measuring intramolecular distance distributions and conformational energetics using
fluorescence lifetime imaging microscopy (FLIM), simultaneous with recordings of
channel function using patch-clamp fluorometry (PCF). The data from multiple donor-
acceptor sites throughout the channels will be compiled into a four-dimensional map (X,
Y, Z, and energy) of the conformational rearrangements associated with ligand-
dependent and voltage-dependent activation of CNBD channels. Our long-term vision is
to understand the general themes that underlie allosteric regulation of ion channels, and
these experiments promise rapid progress toward this goal. Ultimately, the methods and
principles we discover will be of broad utility for elucidating mechanisms for all allosteric
proteins.

## Key facts

- **NIH application ID:** 10757899
- **Project number:** 5R35GM148137-02
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** William N Zagotta
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $404,300
- **Award type:** 5
- **Project period:** 2023-01-01 → 2027-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10757899

## Citation

> US National Institutes of Health, RePORTER application 10757899, Structural energetics of voltage- and ligand-dependent gating in ion channels (5R35GM148137-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10757899. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*