Figure 2. Mg²⁺ modulation of the voltage sensor function in BK channels.

A, cartoon showing amino acid residues involved in Mg²⁺ binding and interaction with the voltage sensor domain. B, gating currents in the absence and presence of 10 mm Mg²⁺ (black and red traces) in response to various lengths of voltage pulses from −80 mV to +250 mV (top). The ionic current (blue trace) in response to a −80 to +250 mV voltage pulse in 10 mm Mg²⁺ is aligned with gating currents to show the correlation in time courses between channel opening and the decay in Off-gating current amplitude in 10 mm Mg²⁺. Adapted from Yang et al. (2007), ©2007 National Academy of Sciences of the USA.