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Figure 2. Actin cytoskeletal regulation of BK channels is mediated via binding of cortactin to the noncanonical SH3 domain binding motifs. A) Representative traces from excised inside-out patches of HEK 293 cells expressing e22-hemagglutinin (HA), zero-HA, or e22P656:667A-HA channel variants before (control) and after (+ CD) application of 10 µM cytochalasin D to the intracellular face of the patch. Patches expressing e22-HA, zero-HA, and e22P656:667A-HA channels contained five, four, and two channels, respectively. Mean channel open probability (Po) determined from 60 s of recording at + 40 mV in the presence of 0.1 µM free calcium in equimolar potassium gradients is given under each trace. B) Summary bar chart of the effect of actin cytoskeletal manipulation on the activity of the respective BK channel variant expressed as percent change in mean open probability (Po) of channels in the patch with respect to pretreatment control. Patches were exposed for 10 min to 10 µM cytochalasin D under control conditions (CD) or in patches pretreated for 5 min with 5 µM of the actin-stabilizing drug Phalloidin (+ Phal). Data are means SEM (n=6 to 12 patches/group). **P < 0.01 ANOVA with Bonferroni post hoc test vs. respective CD-treated group under control conditions.
