GEVIBench › All sensors › Archer2
Archer2
Archaerhodopsin variant that further suppresses photocurrents (~99× vs Arch WT, producing no peak current) at the expense of slower kinetics and lower sensitivity (60% ΔF/F per 100 mV) than its sibling Archer1 (~55×).
- Category: Opsin GEVI
- Published: 2014-09-15 — Nature Communications 2014
- Derived from: Arch
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 640 nm, emission peak 731 nm (Archer2)
- Tags: Archaerhodopsin, Red, Positive-going
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 0.0016× 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) | — | 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 | +60% | 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 | 0.45% (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) | — | 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) | 3 | Number of published research papers, tracked by GEVIBench, that used the sensor for an experiment (a popularity / track-record measure). |
Measurements and sources
ΔF/F per 100 mV
- +60%, 1P — Flytzanis 2014, Fig. 1d
Brightness comparisons
- 3× the brightness of Arch — Flytzanis 2014, Fig. 1a
- 0.0163× the brightness of EGFP — Nikolaev 2025, Table 2
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: -15%; -80 mV: -4%; -70 mV: 0%; -60 mV: 5%; -50 mV: 11%; -40 mV: 18%; -20 mV: 30%; 0 mV: 42%; 20 mV: 54%; 30 mV: 58%; 50 mV: 70% — Flytzanis 2014, Fig. 1d
Research papers using Archer2 (3)
- 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, in vitro)
- 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, et al., ACS Physical Chemistry Au 2024 (Computational modeling and HEK293T cells, in vitro)
- Semirational Protein Engineering Yields Archaerhodopsin-3-Based Fluorescent Genetically Encoded Voltage Indicators with Enhanced Brightness and Red Shifted Absorption Bands — Nikolaev DM, et al., Chem & Bio Engineering 2025 (E. coli and 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.