GEVIBench › All sensors › Cepheid1b
Cepheid1b
Red eFRET voltage indicator built by inserting the bright RFP donor mScarlet-I1.4 into the first extracellular loop of Ace(D81C) rhodopsin; the brighter (but less photostable) member of the Cepheid1 pair.
- Category: eFRET GEVI
- Published: 2023-11-24 — Science Advances 2023
- Derived from: VARNAM
- Response polarity: negative-going (fluorescence decreases on depolarization)
- Spectrum: excitation peak 570 nm, emission peak 600 nm (Cepheid1b)
- Tags: Ace opsin, mScarlet-I1.4, Red, FRET, Somatic targeting
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 1.40× 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) | 2.7 / 5.0 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 | -31% | 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 | 0.4% (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 | 12.1% | 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) | 7 ms | Full width at half maximum of the optical spike waveform. |
| Photostability t75% @ 100 mW/mm² | 17 s | 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 2.71 ms, τ_off 4.99 ms at 25°C — Han 2023, Fig. S7B
- τ_on 2.74 ms, τ_off — ms at 25°C — Yang 2024, Main text
ΔF/F per 100 mV
- -31%, 1P — Han 2023, Fig. S7A
ΔF/F per action potential
- 12.1%, 1P — Han 2023, Fig. 1C
AP width (FWHM)
- 7 ms at 484 Hz sampling, cultured rat hippocampal neurons, in vitro, 1P — Han 2023, Fig. 1D
Brightness comparisons
- 1.65× the brightness of VARNAM — Han 2023, Fig. S5
Photobleaching
- t75% = 108 s at 15.9 mW/mm², 1P — Han 2023, Fig. S6A
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: 10%; -80 mV: 3%; -70 mV: 0%; -60 mV: -5%; -40 mV: -12%; -20 mV: -19%; 0 mV: -25%; 20 mV: -30%; 40 mV: -33% — Han 2023, Fig. 1B
Research papers using Cepheid1b (2)
- Bright and sensitive red voltage indicators for imaging action potentials in brain slices and pancreatic islets — Han Y, Yang J, Li Y, Chen Y, Ren H, Ding R, Qian W, Ren K, Xie B, Deng M, Xiao Y, Chu J, Zou P, Science Advances 2023 (HEK293T cells, in vitro; rat hippocampal neurons, in vitro; mouse cortex, hippocampus, cerebellum, thalamus, habenula, acute brain slices; mouse pancreatic islets, ex vivo)
- Solaris: a panel of bright and sensitive hybrid voltage indicators for imaging membrane potential in cultured neurons — Yang J, Zhu S, Yang L, Peng L, Han Y, Hayward RF, Park P, Hu D, Cohen AE, Zou P, bioRxiv 2024 (HEK293T cells, in vitro (Cepheid1b measured as a comparator: voltage-clamp response half-time τ1/2 = 1.9 ± 0.1 ms at 1058 Hz))
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.