Mechanisms controlling current in ion channels
Potassium currents are an essential part of electrical signalling in all cells, responsible for a functioning central nervous system as well as the activity of cardiac, renal and other organs.
Potassium conduction across cell membranes occurs through the highly selective pore of K+ channels, and is regulated by cellular and electrical signals. The flow of ions is controlled by means of molecular gates in the permeation pathway that alter the energetics of permeation.
Our main objective is to determine the nature of these gate(s) and pin down the mechanisms that cause the channel to switch between conducting and non-conducting states. While the ‘gate’ has historically been ascribed to a narrow cytoplasmic aperture at the junction of four transmembrane helices (one from each subunit), we have provided novel evidence attesting to greater complexity within the system, showing that conduction status is correlated to subtle conformational changes in a conserved intracellular assembly, irrespective of aperture width.