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Updated: Jul 30, 2025
08:39
Whole-cell Patch-clamp Recordings for Electrophysiological Determination of Ion Selectivity in Channelrhodopsins
Published on: May 22, 2017
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A light-gated cation channel with high reactivity to weak light
Shoko Hososhima1,2, Shinji Ueno3,4, Satoshi Okado3
1Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan.
Scientific Reports
|May 10, 2023
Summary
Researchers explored five light-gated cation channelrhodopsins (GtCCR1-5) from Guillardia theta. GtCCR4 demonstrates high light sensitivity and temporal precision for optogenetic neuronal activation, outperforming existing channelrhodopsins (ChRs).
Area of Science:
- Optogenetics
- Neuroscience
- Algal Biology
Background:
- Cryptophyte algae Guillardia theta has 46 microbial rhodopsin-homologous genes.
- Five functionally light-gated cation channelrhodopsins (GtCCR1-5) are distinct from chlorophyte channelrhodopsins (ChRs).
Purpose of the Study:
- Characterize the ion channel properties of GtCCR1-5.
- Compare their performance with ChR2 and other optogenetic ChRs.
- Evaluate GtCCR4 for neuronal activation applications.
Main Methods:
- Functional characterization of GtCCR1-5 ion channel properties.
- Comparison of light sensitivity (EC50) with ChR2.
- Expression of GtCCR4 in cortical neurons and retinal ganglion cells (rd1 mouse model).
Main Results:
- GtCCR1-3 showed light sensitivity similar to ChR2 (EC50: 0.21-1.16 mW/mm²).
- GtCCR4 and GtCCR5 exhibited significantly higher light sensitivity (EC50: 0.025-0.032 mW/mm²).
- GtCCR4 triggered action potentials in neurons with high temporal resolution and lower light power, and showed a high-sensitivity response in blind retinal cells.
Conclusions:
- GtCCR4 offers superior light sensitivity and temporal precision for optogenetic neuronal activation.
- GtCCR4 represents a promising tool for optogenetics, particularly for applications requiring low light power.
- This study expands the toolkit of channelrhodopsins available for neuroscience research.
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