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. 2023 Aug 17;12:e83975. doi: 10.7554/eLife.83975

Figure 1. Photocurrent properties of channelrhodopsins.

(A) Representative photocurrent traces of GtCCR4-3.0-EYFP (GtCCR4-3.0), GtCCR4-MT-P2A-TagCFP (GtCCR4-MT), KnChR, CrChR2[T159C], CoChR, and ChrimsonR. Electrophysiological recordings were performed. Membrane voltage was clamped at –60 mV. Illumination sources were 511 nm light (GtCCR4-3.0, GtCCR4-MT), 469 nm light (KnChR, CrChR2[T159C], CoChR), and 590 nm light (ChrimsonR) at 1.4 mW/mm2. (B) Photocurrent amplitude. Gray bar: peak photocurrent (Ip); white bar: steady state photocurrent (Iss) (n = 6–9). Wilcoxon rank-sum test (CrChR2[T159C]-mCherry Ip vs. Iss, p=0.025; CoChR-tdTomato Ip vs. GtCCR4-3.0-EYFP Ip, p=0.025; ChrimsonR Ip vs. GtCCR4-3.0-EYFP Ip, p=0.049). (C) Comparison of the channel closing kinetics after shutting-off light (τoff) (n = 6–9), Wilcoxon rank-sum test (KnChR-EYFP vs. GtCCR4-3.0-EYFP, p=0.0002; ChrimsonR vs. GtCCR4-3.0-EYFP, p=0.0004). (D) The action spectrum of GtCCR4-3.0 (green circle), KnChR (blue circle), CrChR2[T159C] (purple circle), CoChR (light blue circle), and ChrimsonR (red circle). Illumination sources were 385, 423, 469, 511, 555, 590, or 631 nm light at 1.4 mW/mm2 (GtCCR4-3.0, CrChR2[T159C]) or 0.14 mW/mm2 (KnChR, CoChR, ChrimsonR) (n = 5–10). (E) Half saturation maximum (EC50) of the peak photocurrent (gray bar) and the steady-state photocurrent (white bar) are shown (n = 5, 6), Wilcoxon rank-sum test (CrChR2[T159C]-mcherry Ip vs. Iss, p=0.0079; CrChR2[T159C]-mCherry Ip vs. GtCCR4-3.0-EYFP Ip, p=0.0086; ChrimsonR Ip vs. GtCCR4-3.0-EYFP Ip, p=0.0021; ChrimsonR Iss vs. GtCCR4-3.0-EYFP Iss, p=0.0021). *p<0.05, **p<0.01, ***p<0.001, ****p<0.0005, Mean and SEM are indicated.

Figure 1—source data 1. Data for Figure 1, photocurrent properties of ChRs.

Figure 1.

Figure 1—figure supplement 1. Light power dependency of photocurrent amplitude of GtCCR4-3.0 (A), KnChR (B), CrChR2[T159C] (C), CoChR (D), and ChrimsonR (E).

Figure 1—figure supplement 1.

Photocurrent amplitude at − 60 mV was plotted as a function of light power. 511 nm light (A), 469 nm light (B, C), and 590 nm light (D) were illuminated. Filled circle: peak photocurrent; open circle: steady-state photocurrent (n = 5, 6). Error bars indicate standard errors of the mean (SEMs).
Figure 1—figure supplement 1—source data 1. Data for Figure 1—figure supplement 1, light power dependencies of photo current amplitude of ChRs.