BK channels

Large conductance Ca²⁺-activated K⁺ (BK) channels are activated by membrane depolarization and intracellular Ca²⁺. BK channels regulate membrane potential, intracellular Ca²⁺ concentration and ion transportation across the cell membrane. BK channels are composed of four Slo1 subunits that may associate with β and γ regulatory subunits. The Slo1 subunit contains a transmembrane voltage-sensor domain and a pore-gate domain as well as a cytosolic domain that serves as the Ca²⁺ sensor. BK channels exhibit an intrinsic opening in the absence of stimulation. Voltage and Ca²⁺ activate BK channels with allosteric mechanisms such that the activation of each voltage or Ca²⁺ sensor enhances pore opening. Peptide toxins, fatty acids and small molecule compounds are found to interact with the channel protein to inhibit or enhance BK channel function.