Figure 2
From: Conversion of a light-driven proton pump into a light-gated ion channel
Current traces and IStat(E) of CsR-WT, CsR-D86T and CsR-D211N at different extracellular pH values.
(a) Photocurrents of CsR-WT were less dependent on pH and always outward directed (550 ± 25 nm). (b) IStat(E) of stationary photocurrents of CsR-WT (550 ± 25 nm, normalized to pH 7.5 and 0 mV, pH 10 [n = 10], pH 7.5 [n = 25], pH 5 [n = 7]). (c) Photocurrents of CsR-D86T upon illumination with green light (550 ± 25 nm). Inward-directed peak currents were observed, especially at low pHo. These are followed by outward directed peaks immediately after illumination. (d) Action spectra show two separated protein populations of CsR-D86T. Both are shifted towards CsR-WT as shown by dotted lines. Spectrum of stationary currents was measured at pH 10 and 0 mV (n = 4). Spectrum of peak currents in green was measured at pH 7.5 and 0 mV (n = 4). (e) Stationary photocurrent traces of CsR-D86T upon illumination with blue light (400 ± 25 nm). Stationary currents disappear at low pH. (f) IStat(E) of stationary currents of CsR-D86T (400 ± 25 nm, normalized to pH 10 and 0 mV, pH 10 [n = 13], pH 7.5 [n = 8], pH 5 [n = 5]). (g) Photocurrents of CsR-D211N are directed outward and inward at high and low pHo, respectively (550 ± 25 nm). (h) IStat(E) of stationary photocurrents of CsR-D211N (550 ± 25 nm, normalized to pH 7.5 and 0 mV, pH 10 [n = 6], pH 7.5 [n = 7], pH 5 [n = 6]). Data were measured in oocytes and represent the mean ± SE.
