Effects of swapping TM segments on the modulatory functions of BKγ subunits. Voltage dependence of BK channel activation in the presence of BKγ subunit chimeras, whose main bodies were from different γ subunits and whose TM segments were from γ1 (A), γ2 (B), γ3 (C), and γ4 (D). Thick dot lines are used for the major wild-type BKγ protein(s) intended for comparison. Error bars represent ± SEM.