GEVIBench › All sensors › CAESR
CAESR
Pioneering opsin-FRET voltage indicator fusing Citrine to the QuasAr2 archaerhodopsin quencher; the prototype of the QuasAr-based eFRET sensor lineage.
- Category: eFRET GEVI
- Published: 2014-08-13 — Nature Communications 2014
- Response polarity: negative-going (fluorescence decreases on depolarization)
- Spectrum: excitation peak 516 nm, emission peak 529 nm (CAESR)
- Tags: Yellow, Citrine, Archaerhodopsin, QuasAr2
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 1.43× 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) | 9.9 / 15 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 | -13.1% | 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 | 0.14% (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 | 9.7% | 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) | 2 | 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 9.9 ms, τ_off 14.8 ms at 23°C — Zou 2014, Table 1
ΔF/F per 100 mV
- -13.1%, 1P — Zou 2014, Table 1
ΔF/F per action potential
- 9.7%, 1P — Zou 2014, Table 1
Brightness comparisons
- 1.428× the brightness of EGFP — Zou 2014, Table S1
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: 4%; -70 mV: 0%; -50 mV: -3%; 0 mV: -8%; 50 mV: -12%; 100 mV: -15% — Zou 2014, Fig. 4b
Research papers using CAESR (2)
- Bright and fast multicoloured voltage reporters via electrochromic FRET — Zou P, Zhao Y, Douglass AD, Hochbaum DR, Brinks D, Werley CA, Harrison DJ, Campbell RE, Cohen AE, Nature Communications 2014 (HEK293 cells, in vitro; cultured rat hippocampal neurons, in vitro)
- Two-photon lifetime imaging of voltage indicating proteins as a probe of absolute membrane voltage — Brinks D, Klein AJ, Cohen AE, Biophysical Journal 2015 (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.