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. 2000 Feb 18;97(5):2326–2331. doi: 10.1073/pnas.030438797

Figure 6.

Figure 6

Isoform-specific residues of IP-loop and IVS6 determine external QX access. (A) Effects of IVS6 mutant and double mutant of IP-loop and IVS6 on block by externally applied QX222. Actions of externally applied 500 μM QX222 were studied for μ1-C1572T (▪) and μ1-Y401C/C1572T (▴). The mean values of block for μ1-WT (○) and μ1-Y401C (•) are from Fig. 2C. The bar indicates the period of exposure to 500 μM QX222 in the bath solution. The protocol was the same as that in Fig. 2, and peak currents were normalized to that in control. Data represent the means ± SEM from six oocytes for μ1-C1572T and five for μ1-Y401C/C1572T. (B) Effects of μ1-C1572T and μ1-Y401C/C1572T on recovery from internally applied QX222 block. Recovery from QX222 block was monitored at the indicated intervals after use-dependent block by 1-Hz stimulation for μ1-C1572T (■) and μ1-Y401C/C1572T (▴). Recovery data for μ1-WT (○) and μ1-Y401C (●) are from Fig. 3C. The smooth lines are single exponential fits, and data represent the means ± SEM from four to five oocytes for μ1-C1572T and three for μ1-Y401C/C1572T. For others, see Fig. 3C.