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Arch
The first archaerhodopsin-based voltage indicator, establishing that microbial opsins can optically report membrane potential, though with extremely dim baseline fluorescence.
- Category: Opsin GEVI
- Published: 2011-11-27 — Nature Methods 2012
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 558 nm, emission peak 687 nm (Arch)
- Tags: Archaerhodopsin, Red
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 0.00030× EGFP | Molecular brightness relative to EGFP (extinction coefficient × quantum yield, or a measured ratio). Sensors not measured against EGFP directly are placed through a chain of pairwise brightness comparisons, combined by geometric mean. |
| Kinetics τ_on / τ_off (ms) | 0.50 / 0.50 ms | Activation / decay time constants in ms (amplitude-weighted mean τ for multi-exponential fits). The value shown averages the measurements made at physiological temperature (≥33 °C); if there are none, it is the measurement closest to 33 °C. |
| ΔF/F per 100 mV | +45% (median of 2 measurements: +42.5%) | Steady-state fluorescence change for a 100 mV depolarization step (−70 → +30 mV); the sign gives the polarity. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting. |
| ΔF/F per mV | 0.17% (estimated from the F–V curve) | Subthreshold sensitivity: fluorescence change per mV near rest (−90 to −50 mV). Where no value is reported directly, it is estimated from the F–V curve. |
| ΔF/F per AP | — | Fluorescence change per single action potential in neurons. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting. |
| AP width (FWHM, ms) | 4.3 ms | Full width at half maximum of the optical spike waveform. |
| Photostability t75% @ 100 mW/mm² | — | Time for fluorescence to fall to 75% of its initial value under one-photon illumination, linearly dose-scaled to 100 mW/mm² (t50% is used where the 75% crossing falls inside a fast initial transient). Two-photon curves are not dose-scaled and are excluded. |
| Papers using it (N_used) | 10 | Number of published research papers, tracked by GEVIBench, that used the sensor for an experiment (a popularity / track-record measure). |
Measurements and sources
Kinetics
- τ_on 0.5 ms, τ_off 0.5 ms at 24°C — Kralj 2012, Fig. 1d
- τ_on 0.6 ms, τ_off 0.8 ms at 23°C — Hochbaum 2014, Table S2
ΔF/F per 100 mV
- +45%, 1P — Kralj 2012, Fig. 1c
- +40%, 1P — Hochbaum 2014, Fig. 1c
AP width (FWHM)
- 4.3 ms at 2000 Hz sampling, Cultured rat hippocampal neurons, in vitro, 1P, 24°C — Kralj 2012, Fig. 2f
Brightness comparisons
- 0.00016× the brightness of EGFP — Herasymenko 2025, Table 1
- 0.2× the brightness of Archer1 — Flytzanis 2014, Fig. 1a
- 0.3333333333333333× the brightness of Archer2 — Flytzanis 2014, Fig. 1a
- 0.0006858710562414266× the brightness of FlicR1 — Monakhov 2020, Table 1
- 0.00205761316872428× the brightness of nirButterfly — Monakhov 2020, Table 1
- 0.06578947368421052× the brightness of QuasAr1 — Hochbaum 2014, Table S2
- 0.05× the brightness of QuasAr1 — Monakhov 2020, Table 1
- 0.29411764705882354× the brightness of QuasAr2 — Hochbaum 2014, Table S2
- 0.03571428571428571× the brightness of SomArchon — Monakhov 2020, Table 1
- 0.0004374453193350831× the brightness of VARNAM — Monakhov 2020, Table 1
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -150 mV: -13%; -120 mV: -8%; -90 mV: -4%; -70 mV: 0%; -60 mV: 1%; -30 mV: 4%; 0 mV: 9%; 30 mV: 11%; 60 mV: 13%; 90 mV: 17%; 120 mV: 18%; 150 mV: 21% — Maclaurin 2013, Fig. 2A
Research papers using Arch (10)
- Optical recording of action potentials in mammalian neurons using a microbial rhodopsin — Kralj JM, Douglass AD, Hochbaum DR, Maclaurin D, Cohen AE, Nature Methods 2012 (Cultured rat hippocampal neurons, HEK293 cells, in vitro)
- Mechanism of voltage-sensitive fluorescence in a microbial rhodopsin — Maclaurin D, Venkatachalam V, Lee H, Cohen AE, Proceedings of the National Academy of Sciences 2013 (HEK293 cells and cultured neurons, in vitro)
- Enhanced archaerhodopsin fluorescent protein voltage indicators — Gong Y, Li JZ, Schnitzer MJ, PLoS One 2013 (Cultured rat hippocampal neurons, in vitro)
- Archaerhodopsin voltage imaging: synaptic calcium and BK channels stabilize action potential repolarization at the Drosophila neuromuscular junction — Ford KJ, Davis GW, Journal of Neuroscience 2014 (Drosophila neuromuscular junction, in vivo)
- Archaerhodopsin variants with enhanced voltage-sensitive fluorescence in mammalian and Caenorhabditis elegans neurons — Flytzanis NC, Bedbrook CN, Chiu H, Engqvist MKM, Xiao C, Chan KY, Sternberg PW, Arnold FH, Gradinaru V, Nature Communications 2014 (Cultured rat hippocampal neurons and C. elegans neurons, in vitro/in vivo)
- All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins — Hochbaum DR, Zhao Y, Farhi SL, Klapoetke NC, Werley CA, Kapoor V, Zou P, Kralj JM, Maclaurin D, Smedemark-Margulies N, Saulnier JL, Boulting GL, Straub C, Cho YK, Melkonian M, Wong GKS, Harrison DJ, Murthy VN, Sabatini BL, Boyden ES, Campbell RE, Cohen AE, Nature Methods 2014 (HEK293 cells, cultured rat hippocampal neurons, in vitro)
- Photoactivated voltage imaging in tissue with an archaerhodopsin-derived reporter — Chien MP, Brinks D, Testa-Silva G, Tian H, Brooks FP, Adam Y, Bloxham B, Gmeiner B, Kheifets S, Cohen AE, Science Advances 2021 (Cultured rat hippocampal neurons, acute mouse brain slices, in vitro/in vivo)
- Rational design of far-red archaerhodopsin-3-based fluorescent genetically encoded voltage indicators: from elucidation of the fluorescence mechanism in Archers to novel red-shifted variants — Nikolaev DM, Mironov VN, Metelkina EM, et al., ACS Physical Chemistry Au 2024 (Computational modeling and HEK293T cells, in vitro)
- Archaerhodopsin 3 is an ideal template for the engineering of highly fluorescent optogenetic reporters — Herasymenko K, Walisinghe D, Konno M, Barneschi L, de Waele I, Sliwa M, Inoue K, Olivucci M, Haacke S, Chemical Science 2025 (Protein engineering and spectroscopic characterization)
- Semirational protein engineering yields archaerhodopsin-3-based fluorescent genetically encoded voltage indicators with enhanced brightness and red shifted absorption bands — Nikolaev DM, Metelkina EM, Domskii NA, et al., Chemical & Biomedical Engineering 2025 (HEK293T cells, in vitro)
Data and citation
- llms.txt — summary for language models
- llms-full.txt — every sensor in full (Markdown)
- gevis.json — all values and measurements with sources (JSON)
- gevis.csv — one row per sensor (CSV)
Cite GEVIBench as: Adam E. Cohen and Daozheng Gong (2026). Voltage imaging: A practical guide. Neuron. https://doi.org/10.1016/j.neuron.2026.08.002
Generated from the GEVIBench database on 2026-10-12.