FIGURE 7.

Mean inhibitory effect of Cd²⁺ on channels bearing cysteine side chains in TM1. Shown is the mean effect of 100 μm Cd²⁺ on macroscopic current amplitude for two single cysteine mutants (K95C, Q98C; black bars) and 19 double cysteine mutants that combine the TM1 cysteine listed above the panel with the TMs 6 or 12 cysteine listed below. Daggers indicate three mutants that did not express measureable macroscopic current in inside-out patches. Asterisk indicates a significant difference from the corresponding single cysteine mutant in TMs 6 or 12 (p < 0.000005). Error bars indicate the means ± S.E. from 3–5 patches.