BK channels: integrators of cellular signals in health and disease

Calcium- and voltage-gated, large conductance potassium (BK) channels, also known as Slo1 or “Maxi-K” channels, play a crucial role in a vast number of physiological and pathophysiological conditions. BK channels are found in excitable and non-excitable tissues in eukaryotes. The function of these channels is to repolarize any excited membrane by passing a potassium outward current, in response to depolarization and/or increase in local calcium levels. Thus, voltage and calcium ions are involved in gating the channel under physiological conditions. This dual activation makes them perfect sensors for many cellular events that require integration between intracellular calcium levels and electrical signals. BK channels contribute to action potential repolarization, control of transmitter release and control of vascular tone; they play a role in hormone secretion, hearing, breathing and seizure activity; finally, BK channels are main targets for important ligands like alcohol and gaseous neurotransmitters, such as NO, CO or H2S, to name a few. In the last years, the molecular entities and mechanisms involved in modulation of BK channels have gained tremendous attention, as the key role of these channels in cellular processes became increasingly recognized. Indeed, accessory proteins such as slob, beta and gamma subunits, all serve to modulate the channel gating characteristics. Moreover, channel subunit expression and function is further tuned by phosphorylation/ dephosphorylation processes, redox mechanisms and the lipid microenvironment of the BK channel protein complex. This research topic welcomes contributions to structural and functional aspects of BK channels, channel modulation by a variety of agents and cellular components, as well as the channel’s relevance in health and disease.