Xenbase Image ID: 124725

Figure 13. Neutralization of charged residues in the S1–S4 segment does not eliminate voltage-dependent gating of Slo2.1 channels. (A and B) I-V relationships for currents recorded from oocytes expressing S1 mutant K70A Slo2.1 (n = 14) or R80A Slo2.1 (n = 7) channels before and after treatment with 1 mM NFA. Extracellular solution was K104. Oocytes were recorded 2 d after injection of 2.5 ng cRNA. (C) I-V relationships for currents recorded from oocytes expressing the S2 double mutant (E118A/E143A) Slo2.1 channels before and after treatment with 1 mM NFA (n = 7). Oocytes were recorded 2 d after injection of 2.5 ng cRNA. (D) G-V relationships for WT and S1–S3 mutant channels. Dotted curve shows relationship predicted by GHK current equation for voltage-independent channel. The data were fitted with a Boltzmann function (smooth curves) to obtain V1/2 and z values as follows. WT: V1/2 = +95 ± 0.6 mV and z = 0.48 ± 0.01; K70A: V1/2 = +159 ± 8 mV and z = 0.30 ± 0.04; R80A: V1/2 = +116 ± 3 mV and z = 0.48 ± 0.02; E118A/E143A: V1/2 = +114 ± 4 mV and z = 0.51 ± 0.04. (E) I-V relationships for currents recorded from oocytes expressing the S4 neutral mutant (K174A/E178A/D183A/R186A/H175A/H185A) Slo2.1 channels before and after treatment with 1 mM NFA (n = 9). Oocytes were recorded 3 d after injection of 9.2 ng cRNA. (F) G-V relationships for WT and S4 neutral mutant channels (+84 ± 1 mV; z = 0.69 ± 0.02). Dotted curve shows relationship predicted by GHK current equation for voltage-independent channel. (G) Normalized I-V relationships for WT and S1–S4 mutant channels. Currents for each channel type were normalized to their average values measured at +120 mV. Image published in: Dai L et al. (2010) © 2010 Dai et al. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View

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