XB-IMG-126661
Xenbase Image ID: 126661
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Figure 6. Using macropatches to explore the mechanism of activation of BK channels by Mg2+. (A) Representative current traces from macropatches containing hundreds of channels held at a constant −50 mV for 0 Mg2+ (left) and 10 mM Mg2+ (right). Because the Po of each individual channel is so low, typically only one channel is open at any time. The indicated part of the upper recordings is expanded tenfold three successive times to show the data on faster time bases. Most openings in 0 Mg2+ are unit bursts consisting of single openings. Mg2+ increased open interval duration. Mg2+ also increased the frequency of openings by increasing the number of openings per burst and decreasing the duration of closed intervals (gaps) between bursts. (B) When the voltage sensors were held deactivated by the R167E mutation, 10 mM Mg2+ no longer enhanced channel activation. (C) When the voltage sensors were held constitutively activated by the R210C mutation, Mg2+ still activated the channels at −200 mV. Image published in: Chen RS et al. (2011) © 2011 Chen et al. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View |