High resolution

Module 3: Figure BK channel opening

Large-conductance (BK) channel opening by both membrane depolarization (electromechanical coupling) and by intracellular Ca2+ (chemomechanical coupling).

The opening mechanism seems to depend upon a displacement of transmembrane domain 6 (TM6) brought about by a movement of the regulator of K+ conductance, which is attached to the end of TM6. The nature of the conformational changes that occur following the movement of the voltage sensor (yellow arrow) or the displacement of the regulator following the binding of Ca2+ remains to be determined.