Figure 1.

Ion selectivity of GtACR1-driven photocurrents in HEK 293T cells. (A–F) Representative whole-cell currents at holding membrane potentials from −60 mV to +60 mV (step size 20 mV). Peak current I_P is indicated. The calculated reversal potential E_{rev, cal} is stated at 25°C. Standard pipette solution contained 54 mM Cl⁻ and 0 mM Na⁺. External bath solution contained (A) standard high, (B) moderately reduced and (C) strongly reduced Cl⁻ concentration. (D) Photocurrent using an alkaline external solution (pH 9.0), Cl⁻ concentrations as in (A). (E,F) Photocurrent at moderately reduced (E) and strongly reduced Na⁺ concentration (F), Cl⁻ concentrations as in (A). (G) IE relationship recorded at different external Cl⁻ concentrations (n = 8–12). Mean reversal potentials (E_rev) ± SE are marked in the respective color. (H) IE relationship recorded at pH 7.4 and pH 9.0 (n = 8–12, Mann-Whitney p > 0.05). (I) IE relationship recorded at various Na⁺ concentrations (n = 10–12, Mann-Whitney p > 0.05).