XB-IMG-124951
Xenbase Image ID: 124951
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Figure 5. Relationship between E519C:C445V:C449V fluorescence signal and ionic conductance.(A) Representative current (above) and fluorescence traces (below) recorded using the same protocol as in Fig. 2A. (B) Comparison of G-V curve (squares, V½â=ââ18.3±1.2, kâ=â8.8±0.2 mV, nâ=â7) with fluorescence-voltage relationship from the tail of fluorescence (circles, F-VOFF; V½â=ââ20.6±1.2 mV, kâ=â11.4±0.6 mV, nâ=â16), measured at the times indicated by the symbols in panel A, and with fluorescence-voltage relationship from the peak fluorescence quenching upon depolarization (F-VON, triangles in panel A). The F-VON curve was obtained by plotting the maximum amplitude of the downward deflection for each trace, and normalized to +20 mV (estimated saturation voltage), and was best fit with a double Boltzmann function, as a second component appears at positive potentials (first phase: V½,1â=ââ37.8±1.7 mV, k1â=â13.7±0.7 mV; F-VON second phase: V½,2â=â43.5±7.9, k2â=â9.6±2.6 mV, nâ=â13; A1â=â0.96±0.2). (C) Representative fluorescence traces obtained during 500 ms depolarizing steps from â80 to potentials ranging from â90 to 100 mV. Membrane was then hyperpolarized at â110 mV for 500 ms. (D) Normalized G-V relationship (squares, V½â=ââ19.6±2.0, kâ=â13.8±2.7 mV, nâ=â3) obtained as in A compared to F-VON (first phase: V½,1â=ââ46.7±2.1 mV, k1â=â12.7±1.1 mV; F-VON second phase: V½,2â=â56.7±7.2, k2â=â16.9±3.9 mV, nâ=â3; A1â=â0.56±0.05). The inset shows the fluorescence signal from a representative cell, to highlight the first saturation step at about 0 mV and the second saturation step at about 80 mV. Image published in: Es-Salah-Lamoureux Z et al. (2010) Es-Salah-Lamoureux et al. Creative Commons Attribution license Larger Image Printer Friendly View |