Experimental challenges in ion channel research: uncovering basic principles of permeation and gating in potassium channels

Biological ion channels precisely control the flow of ions across membranes in response to a range of physical and chemical stimuli. With their ability of transporting ions in a highly selective manner and of integrating regulatory cues, they are a source of inspiration for the construction of solid-state nanopores as sensors or switches for practical applications. Here, we summarize recent advancements in understanding the mechanisms of ion permeation and gating in channel proteins with a focus on the elementary steps of ion transport through the pore and on non-canonical modes of intramolecular communication between peripheral sensory domains and the central channel pore. [GRAPHICS] . Modalities of gating in potassium (K+) channels- Schematic view of a K+ channel shown as a dimer for simplicity. The functional domains (in grey) are marked on one monomer only as follow: pore domain (PD), voltage sensor domain (VSD), cytosolic domain (CD). IN and OUT indicate sides of the membrane, marked by horizontal black lines. Black spheres indicate K+ ions passing through the pore. Black arrows indicate the modalities of pore gating discussed in the article.