Figure 1.
Full modulation of BK channels by the BKγ1’s TM segment and neighboring positively charged cluster transplanted into the structurally unrelated β1 subunit. (A) Representative traces of recorded BK channel currents in response to the depolarization of membrane potential from −80 to 200 mV in the absence and presence of the β1, γ1, and β1/γ1 chimeras. The voltage pulse protocol used to obtain the current traces is shown on the left side, and the schematic structures in the ER membrane are shown on top. (B and C) Voltage dependence of BK channel activation (plotted from tail currents at −120 mV) in the absence and presence of wild-type β1, γ1, and β1/γ1 chimeric subunits (B) and in the absence and presence of γ1 and β1/γ1 chimeric subunits with mutation F273S/V275A in the middle of the γ1 TM segment (C). 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. Error bars represent ±SEM.