Figure 3
Voltage-dependent DPA-induced effects on patch-clamped HEK293 cells expressing the plasma membrane-targeted CFP-YFP Rho-pYC tandem. (A) Time course of the fluorescent response on voltage pulses from −120 to +120 mV (upper left panel) in the presence of 10 μM DPA. A fluorescence image of the cells (100x oil-immersion objective) demonstrating the marked plasma membrane distribution of the Rho-pYC signal is shown on the right. Representative fluorescence traces at excitation wavelengths of 440 (CFP) and 510 nm (YFP) are shown. Averaged responses from 50 trials delivered at 1 s intervals are illustrated on the graphs. Expanded sections of the fluorescence traces are shown in the insets. The estimated ΔF/Fo values expressed as % are also indicated. (B) Voltage dependence of the DPA-induced effects. Families of superimposed fluorescence traces in response to voltage steps as illustrated at the top are shown on the upper left panel. Separate traces obtained at +120, 0 and −120 mV are shown on the right. Plots of ΔF/Fo versus voltage with a Boltzmann curve fitted to the data, corresponding to the CFP (circles) and YFP (squares) signals, are shown at the bottom. V1/2 and maximal ΔF/Fo values obtained from the curves are indicated.
