Heme-Driven Conformational Changes in the Human Slo1 BKCa Channel Gating Ring

Abstract

Large-conductance voltage- and Ca2+-activated K+ channels (BKCa) are regulated by signaling molecules acting on two intracellular Regulator of K+ Conductance (RCK) domains which assemble into a gating ring superstructure. The discovery of heme as a BKCa channel modulator has unveiled novel aspects of its physiological function (Tang et al., Nature 2003). A recent study (Horrigan et al., JGP 2005) suggests that heme induces conformational changes within the BKCa gating ring altering its interaction with the voltage sensor.