GEVIBench › All sensors › HASAP1
HASAP1
Chemigenetic adaptation of the ASAP architecture that replaces cpGFP with cpHaloTag labeled with a far-red Si-rhodamine dye, giving positive-going fluorescence responses to depolarization.
- Category: Chemigenetic GEVI
- Published: 2021-04-01 — Nature Chemical Biology 2021
- Derived from: ASAP1
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 642 nm, emission peak 655 nm (HASAP1 (JF635))
- Plasmid: Addgene #138325
- Tags: cpHaloTag, Far-red, Positive-going, JF635
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 1.81× 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) | 2.2 / 2.4 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 | +9.3% | 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 | 0.075% (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 | 3.7% | 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) | 15 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) | 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 2.22 ms, τ_off 2.4 ms at 25°C — Deo 2021, Table S6
ΔF/F per 100 mV
- +9.3%, 1P, dye JF635 — Deo 2021, Fig. 4e
ΔF/F per action potential
- 3.7%, 1P, dye JF635 — Deo 2021, Fig. 4i
AP width (FWHM)
- 15.3 ms at 400 Hz sampling, Rat, dissociated hippocampal neurons, in vitro (culture), 1P — Deo 2021, Fig. 4i
Brightness comparisons
- 1.808× the brightness of EGFP — Deo 2021, Table S4
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -110 mV: -3%; -90 mV: -2%; -70 mV: 0%; -50 mV: 1%; -30 mV: 2%; -10 mV: 4%; 10 mV: 6%; 30 mV: 9%; 50 mV: 13% — Deo 2021, Fig. 4e
Research papers using HASAP1 (1)
- The HaloTag as a general scaffold for far-red tunable chemigenetic indicators — Deo C, Abdelfattah AS, Bhargava HK, Berro AJ, Falco N, Farrants H, Moeyaert B, Chupanova M, Lavis LD, Schreiter ER, Nature Chemical Biology 2021 (Rat hippocampal 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.