Figure 3

Light dependency of CarO::YFP.

(a) Action spectrum. Effect of light-wavelength on CarO::YFP activity (mean value and standard deviation of 7 cells). The light emitted by a 150W-XBO lamp was filtered through narrow-band filters. At every wavelength the same dose of photons per time and area (2 × 10¹⁶ photons s⁻¹ mm⁻²) was used and values were corrected for eventual intensity loss (reference wavelength 560 nm). The action spectrum was essentially the same at different intracellular proton concentrations (pH 5, 7.4 and 9, Supplementary Fig. S2); therefore, for better signal to noise-ratio, pH of internal pipette solution was set to 5. (b) Dependency of the pump current amplitude on photon density. Mean normalized photocurrent and corresponding standard deviation (5 cells, 3 recordings each). Data were fitted by a Hill function (red curve).