Effects of swapping N-signal peptides and LRRDs on the modulatory functions of BKγ subunits. (A) Representative traces of recorded BK channel currents in response to the depolarization of the membrane potential from −80 mV in 20-mV steps for selected expression constructs. (B–E) Voltage dependence of BK channel activation (plotted from tail currents at −120 mV) in the absence and presence of wild-type BKγ subunits (B); in the presence of γ1 N-signal peptide–swapping chimera (C); in the presence of LRRD-swapping chimera (D); and in the presence of TM and C-tail region–swapping chimera, whose main bodies were from γ1 and whose TM and C-tail regions together were from other BKγ subunits (E). For all indicated given names of chimeric BKγ subunits, the acceptor subunit used to generate the main protein body appears before the slash, and the donor subunit used for a swapped domain or region together with the name of swapped domain or region appears after the slash. All BK channel currents were recorded in the virtual absence of [Ca²⁺]_i and plotted as the normalized conductance (G/Gmax) against different membrane voltages. Thick dot lines are used for the major wild-type BKγ protein(s) intended for comparison. Error bars represent ± SEM.