GEVIBench › All sensors › QuasAr2
QuasAr2
Higher-sensitivity QuasAr variant spike counting and subthreshold event detection.
- Category: Opsin GEVI
- Published: 2014-06-22 — Nature Methods 2014
- Derived from: Arch
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 590 nm, emission peak 715 nm (QuasAr2)
- Two-photon compatible: no
- Plasmid: Addgene #51692
- Tags: Archaerhodopsin, Far-red
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 0.00086× 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) | 1.1 / 1.5 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 | +90% (median of 3 measurements: +46%) | 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 | 0.7% (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 | 48% (median of 2 measurements: 48%) | 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) | 4.5 ms | Full width at half maximum of the optical spike waveform. |
| Photostability t75% @ 100 mW/mm² | 3.1 h | 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) | 23 | 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 4.6 ms, τ_off 4 ms at 23°C — Hochbaum 2014, Table S2
- τ_on 1.4 ms, τ_off 1.3 ms at 34°C — Hochbaum 2014, Table S2
- τ_on 0.9 ms, τ_off 1.6 ms at 33-34°C — Villette 2019, Table 1
- τ_on 4.46 ms, τ_off 6.02 ms at 32°C — Piatkevich 2018, Table S1
ΔF/F per 100 mV
- +90%, 1P — Hochbaum 2014, Fig. 1c
- +46%, 1P — Piatkevich 2018, Fig. 1g
- +46%, 1P — Villette 2019, Table 1
ΔF/F per action potential
- 48%, 1P — Hochbaum 2014, Fig. 1g
- 48%, 1P — Zou 2014, Table 1
AP width (FWHM)
- 4.5 ms at 1000 Hz sampling, Cultured rat hippocampal neuron (Optopatch2), in vitro, 1P, 34°C — Hochbaum 2014, Fig. S5C
Brightness comparisons
- 3.4× the brightness of Arch — Hochbaum 2014, Table S2
- 0.36× the brightness of Archon1 — Piatkevich 2018, Fig. 2b
- 1× the brightness of Archer1 — Monakhov 2020, Table 1
- 0.12484394506866417× the brightness of Archon2 — Piatkevich 2018, Fig. 2b
- 0.0017985611510791368× the brightness of ASAP3 — Villette 2019, Table 1
- 0.5× the brightness of paQuasAr3 — Adam 2019, Ext. Fig. 3f
Photobleaching
- t75% = 513 s at 2200 mW/mm², 1P — Piatkevich 2018, Fig. 2i
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: -17%; -90 mV: -13%; -80 mV: -6%; -70 mV: 0%; -60 mV: 8%; -50 mV: 16%; -40 mV: 25%; -30 mV: 32%; -20 mV: 41%; -10 mV: 51%; 0 mV: 60%; 10 mV: 69%; 20 mV: 77%; 30 mV: 84%; 40 mV: 91%; 50 mV: 98% — Hochbaum 2014, Fig. 1c
Research papers using QuasAr2 (23)
- All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins — Hochbaum DR, Zhao Y, Farhi SL, Klapoetke NC, Werley CA, Kapoor V, Zou P, Kralj JM, Maclaurin D, Smedemark-Margulies N, Saulnier JL, Boulting GL, Straub C, Cho YK, Melkonian M, Wong GKS, Harrison DJ, Murthy VN, Sabatini BL, Boyden ES, Campbell RE, Cohen AE, Nature Methods 2014 (HEK293 cells, cultured rat hippocampal neurons, mouse brain slices, Drosophila in vivo)
- 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 and cultured rat hippocampal neurons, in vitro)
- Genetically targeted all-optical electrophysiology with a transgenic Cre-dependent Optopatch mouse — Lou S, Adam Y, Weinstein EN, Williams LA, Williams K, Parot V, Kavokine N, Liberles S, Madisen L, Zeng H, Cohen AE, Journal of Neuroscience 2016 (Mouse, DRG neurons and brain slices, in vitro/in vivo)
- Optical electrophysiology for probing function and pharmacology of voltage-gated ion channels — Zhang H, Reichert E, Cohen AE, eLife 2016 (HEK293 cells stably expressing NaV channels, in vitro)
- Cardiotoxicity screening with simultaneous optogenetic pacing, voltage imaging and calcium imaging — Dempsey GT, Chaudhary KW, Atwater N, Nguyen C, Brown BS, McNeish JD, Cohen AE, Kralj JM, Journal of Pharmacological and Toxicological Methods 2016 (Human iPSC-derived cardiomyocytes, in vitro)
- All-optical electrophysiology for disease modeling and pharmacological characterization of neurons — Werley CA, Brookings T, Upadhyay H, Williams LA, McManus OB, Dempsey GT, Current Protocols in Pharmacology 2017 (Rat hippocampal neurons and human iPSC-derived neurons, in vitro)
- Ultrawidefield microscope for high-speed fluorescence imaging and targeted optogenetic stimulation — Werley CA, Chien MP, Cohen AE, Biomedical Optics Express 2017 (Cultured neurons expressing Optopatch2, in vitro)
- Geometry-dependent functional changes in iPSC-derived cardiomyocytes probed by functional imaging and RNA sequencing — Werley CA, Chien MP, Gaublomme J, Shekhar K, Butty V, Yi BA, Kralj JM, Bhatt R, Boyer LA, Regev A, Cohen AE, PLOS ONE 2017 (Human iPSC-derived cardiomyocytes, in vitro)
- Evaluation of optogenetic electrophysiology tools in human stem cell-derived cardiomyocytes — Bjork S, Ojala EA, Nordstrom T, Ahola A, Liljestrom M, Hyttinen J, Kankuri E, Mervaala E, Frontiers in Physiology 2017 (Human iPSC-derived cardiomyocytes, in vitro)
- A dimeric fluorescent protein yields a bright, red-shifted GEVI capable of population signals in brain slice — Yi B, Bhatt D, Bhatt R, Baker BJ, Scientific Reports 2018 (Mouse hippocampal brain slices, ex vivo)
- All-optical electrophysiology for high-throughput functional characterization of a human iPSC-derived motor neuron model of ALS — Kiskinis E, Kralj JM, Zou P, Weinstein EN, Zhang H, Tsioras K, Wiskow O, Ortega JA, Eggan K, Cohen AE, Stem Cell Reports 2018 (Human iPSC-derived motor neurons (ALS model), in vitro)
- Optical interrogation of neuronal circuitry in zebrafish using genetically encoded voltage indicators — Miyazawa H, Okumura K, Hiyoshi K, Maruyama K, Kakinuma H, Amo R, Okamoto H, Yamasu K, Tsuda S, Scientific Reports 2018 (Zebrafish, larval brain, in vivo)
- Comparative evaluation of genetically encoded voltage indicators — Bando Y, Sakamoto M, Kim S, Ayzenshtat I, Yuste R, Cell Reports 2019 (Mouse, cultured hippocampal neurons and visual cortex in vivo)
- Electrophysiological characterization of drug response in hSC-derived cardiomyocytes using voltage-sensitive optical platforms — Pfeiffer-Kaushik ER, Smith GL, Cai B, Dempsey GT, Bhatt D, Bhatt R, Hortigon-Vinagre MP, Zamora V, Smith G, Journal of Pharmacological and Toxicological Methods 2019 (Human stem cell-derived cardiomyocytes, in vitro)
- Simultaneous voltage and calcium imaging and optogenetic stimulation with high sensitivity and a wide field of view — Nguyen C, Bhatt D, Bhatt R, Rozsahegyi EJ, Bhatt R, Werley CA, Biomedical Optics Express 2019 (Human iPSC-derived cardiomyocytes, in vitro)
- Rhodopsin-based voltage imaging tools for use in muscles and neurons of Caenorhabditis elegans — Azimi Hashemi N, Bergs ACF, Schuler C, Scheiwe AR, Steuer Costa W, Bach M, Liewald JF, Gottschalk A, Proceedings of the National Academy of Sciences 2019 (C. elegans, body wall muscles and neurons, in vivo)
- Highly parallelized, multicolor optogenetic recordings of cellular activity for therapeutic discovery applications in ion channels and disease-associated excitable cells — Borja G, Zhang H, Harwood J, Jacques K, Bhatt D, Bhatt R, Bhatt R, Werley CA, Frontiers in Molecular Neuroscience 2022 (HEK293 cells expressing NaV channels, in vitro)
- Human cancer cells generate spontaneous calcium transients and intercellular waves that modulate tumor growth — Liang H, Zhang C, Chen H, Liu T, Tanaka T, Wang Y, Biomaterials 2022 (Human colon and prostate cancer cells, in vitro/in vivo)
- All-optical closed-loop voltage clamp for precise control of muscles and neurons in live animals — Bergs ACF, Liewald JF, Rodriguez-Rozada S, Liu Q, Wirt C, Bessel A, Zeitzschel N, Durmaz H, Nozownik A, Dill H, Jospin M, Vierock J, Bargmann CI, Hegemann P, Wiegert JS, Gottschalk A, Nature Communications 2023 (C. elegans, muscles and neurons; rat hippocampal neurons, in vitro/in vivo)
- A phenotypic screening platform for chronic pain therapeutics using all-optical electrophysiology — Liu S, Zhang H, Werley CA, Bhatt D, Bhatt R, Bhatt R, Bhatt D, Bhatt R, PAIN 2024 (Mouse DRG sensory neurons, in vitro)
- A robotic multidimensional directed evolution approach applied to fluorescent voltage reporters — Piatkevich KD, Jung EE, Straub C, Linghu C, Park D, Suk HJ, Hochbaum DR, Goodwin D, Pnevmatikakis E, Pak N, Kawashima T, Yang CT, Rhoades JL, Shemesh O, Asano S, Yoon YG, Freifeld L, Saulnier JL, Riegler C, Engert F, Hughes T, Drobizhev M, Szabo B, Ahrens MB, Flavell SW, Sabatini BL, Boyden ES, Nature Chemical Biology 2018 (HEK293T cells and cultured mouse hippocampal neurons, in vitro)
- Ultrafast two-photon imaging of a high-gain voltage indicator in awake behaving mice — Villette V, Chavarha M, Dimov IK, Bradley J, Pradhan L, Mathieu B, Evans SW, Chamberland S, Shi D, Yang R, Kim BB, Ayon A, Jalil A, St-Pierre F, Schnitzer MJ, Bi G, Toth K, Ding J, Dieudonne S, Lin MZ, Cell 2019 (HEK293 cells, cultured neurons, and mouse brain in vivo)
- Screening and cellular characterization of genetically encoded voltage indicators based on near-infrared fluorescent proteins — Monakhov MV, Matlashov ME, Colavita M, Song C, Shcherbakova DM, Antic SD, Verkhusha VV, Knopfel T, ACS Chemical Neuroscience 2020 (HEK293T cells and cultured mouse 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.