Electrophysiological properties of wild type ReaChR and the mutants E130Q, E163T, D293N, and D196N.
A, representative photocurrent traces recorded upon 500-ms illumination. B, average size of peak (left) and stationary (right) photocurrents; significance was tested with the Mann-Whitney U test. *, 0.05 > p > 0.01; **, 0.01 > p > 0.001; ns, not significant. C, time constants of apparent closing kinetics after light switched off; wild type, E130Q, and D196N were fitted monoexponentially; E163T was fitted biexponentially; and due to decreased currents there is no value for D293N. D, current–voltage relation of wild type (black) and E130Q (gray) under different extracellular ionic conditions (intracellular NaCl, pH 7.2) with corresponding I–E plot (normalized to standard conditions); holding potential (Ehold) = 0 mV in red. E, calculated reversal potentials (Erev) for wild type (filled bars) and E130Q (empty bars) (liquid junction potential-corrected; n = 5–8). F, reversal potential shifts (ΔErev) with respect to standard conditions (NaCl, pH 7.2) after substitution of extracellular Na+ for non-permeable NMG (NMG, pH 7.2; black), reduction of extracellular protons (NaCl, pH 9.0; dark gray), and reduction of both extracellular NaCl and protons (NMG, pH 9.0; light gray) (n = 5–8; liquid junction potential-corrected). Error bars represent standard errors (S. E.).