GEVIBench › All sensors › Positron
Positron
Positive-going Voltron variant with inverted fluorescence polarity.
- Category: Chemigenetic GEVI
- Published: 2020-07-10 — Nature Communications 2020
- Derived from: Voltron
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 534 nm, emission peak 554 nm (Positron (JF525))
- Plasmid: Addgene #129253
- Tags: Ace opsin, HaloTag, Positive-going
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 1.56× 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) | 3.4 / 4.3 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 | +23% (median of 4 measurements: +17.4%) | 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 | 0.25% (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 | 5.9% (median of 2 measurements: 6.2%) | 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 | 48 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) | 3 | 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 3.39 ms, τ_off 4.28 ms at 25°C — Abdelfattah 2020, Table S1
- τ_on 11.27 ms, τ_off 10.76 ms at 25°C — Liu 2025, Table S2
ΔF/F per 100 mV
- +23%, 1P, dye JF525 — Abdelfattah 2020, Fig. 2a
- +20%, 1P, dye JF525 — Abdelfattah 2020, Fig. S4
- +14.7%, 1P, dye JF525 — Liu 2025, Table S2
- +12%, 1P, dye JF525 — Hasseman 2022, Fig. 1
ΔF/F per action potential
- 5.9%, 1P, dye JF525 — Liu 2025, Table S2
- 6.5%, 1P, dye JF525 — Hasseman 2022, Fig. 2
Brightness comparisons
- 0.59× the brightness of Voltron — Abdelfattah 2020, Fig. 2b
- 3.5× the brightness of ASAP4e — Lee 2024, Table S4
Photobleaching
- t75% = 96 s at 50 mW/mm², 1P — Liu 2025, Fig. S7
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -110 mV: -8%; -90 mV: -5%; -70 mV: 0%; -50 mV: 5%; -30 mV: 9%; -10 mV: 12%; 10 mV: 16%; 30 mV: 20%; 50 mV: 24% — Abdelfattah 2020, Fig. 2a
Research papers using Positron (3)
- A general approach to engineer positive-going eFRET voltage indicators — Abdelfattah AS, et al., Nature Communications 2020 (Rat, hippocampal neurons, in vitro; Zebrafish, forebrain, in vivo)
- Positive-going hybrid indicators for voltage imaging in excitable cells and tissues — Liu S, et al., Science Advances 2025 (Rat, hippocampal neurons, in vitro)
- Improving positively tuned voltage indicators for faster kinetics and higher contrast — Lee S, Zhang G, Hao YA, et al., bioRxiv 2024 (Rat, cortical neurons, 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.