Archer1

Archaerhodopsin variant functioning as both a voltage indicator and a light-activated neuronal silencer.

Category: Opsin GEVI
Published: 2014-09-15 — Nature Communications 2014
Derived from: Arch
Response polarity: positive-going (fluorescence increases on depolarization)
Spectrum: excitation peak 627 nm, emission peak 729 nm (Archer1)
Plasmid: Addgene #60423
Tags: Archaerhodopsin, Red, Positive-going

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_EGFP)	0.0011× 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)	2.5 / 5.5 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	+85%	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	0.78% (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	33%	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	55.0 min	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)	6	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 2.5 ms, τ_off 5.5 ms — Bando 2019, Fig. 1M/1N

ΔF/F per 100 mV

+85%, 1P — Flytzanis 2014, Fig. 1d

ΔF/F per action potential

33%, 1P — Flytzanis 2014, Fig. 3e

Brightness comparisons

1× the brightness of QuasAr2 — Monakhov 2020, Table 1
5× the brightness of Arch — Flytzanis 2014, Fig. 1a
0.00367× the brightness of EGFP — Nikolaev 2025, Table 2

Photobleaching

t75% = 150 s at 2200 mW/mm², 1P — Piatkevich 2018, Fig. 2i

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: -19%; -70 mV: 0%; -50 mV: 20%; -25 mV: 42%; 0 mV: 67%; 25 mV: 84%; 50 mV: 105% — Flytzanis 2014, Fig. 1d

Research papers using Archer1 (6)

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; C. elegans AWC-ON neurons, in vivo)
A robotic multidimensional directed evolution approach applied to fluorescent voltage reporters — Piatkevich KD, Jung EE, Straub C, Linghu C, Park D, Suk HJ, Hochbaum DR, Goodwin D, Pnevmatikakis E, Pak N, et al., Nature Chemical Biology 2018 (HEK293T cells and cultured rat hippocampal neurons, in vitro)
Comparative Evaluation of Genetically Encoded Voltage Indicators — Bando Y, Sakamoto M, Kim S, Ayzenshtat I, Yuste R, Cell Reports 2019 (Mouse cortical neurons, in vitro (excluded from in vivo due to low brightness under LED/2P excitation))
Screening and Cellular Characterization of Genetically Encoded Voltage Indicators Based on Near-Infrared Fluorescent Proteins — Monakhov MV, Matlashov ME, Colavita M, Song C, Shcherbakova DM, Antic SD, Verkhusha VV, Knöpfel T, ACS Chemical Neuroscience 2020 (HEK293T cells and 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.