AMBER

First autonomous bioluminescent voltage indicator by pairing a VSD with a self-sufficient luciferase enzyme.

Category: Bioluminescent GEVI
Published: 2021-11-10 — Advanced Biology 2021
Derived from: VSFP2.1
Response polarity: positive-going (fluorescence increases on depolarization)
Spectrum: excitation peak 490 nm, emission peak 528 nm (AMBER)
Bioluminescent: emits light enzymatically, needs no excitation and does not photobleach
Tags: Luciferase, Bioluminescent, Positive-going, YPet, BRET

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_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)	40 / 30 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	+200%	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	—	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	bioluminescent (no photobleaching)	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)	1	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 40 ms, τ_off 30 ms at 25°C — Srinivasan 2021, Fig. 3B

ΔF/F per 100 mV

+200% — Srinivasan 2021, Fig. 2A

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -60 mV: 0%; -40 mV: 14%; -20 mV: 68%; 0 mV: 88%; 20 mV: 97%; 40 mV: 100%; 60 mV: 99% — Srinivasan 2021, Fig. 2B

Research papers using AMBER (1)

An Autonomous Molecular Bioluminescent Reporter (AMBER) for Voltage Imaging in Freely Moving Animals — Srinivasan P, Griffin NM, Thakur DP, Joshi PM, Nguyen-Le A, McCotter S, Jain A, Saeidi M, Kulkarni P, Eisdorfer JT, Rothman JH, Montell C, Theogarajan L, Advanced Biology 2021 (C. elegans, pharyngeal muscle and mechanosensory neurons, in vivo)

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.