The Effect of Membrane Cholesterol Content on the Gating Mechanism of Voltage Gated Potassium Channels

Abstract

Voltage gated ion channels contain the voltage sensing domain (VSD) and the pore forming domain (PD). VSD movement induced by depolarization is transmitted to the PD, and causes the opening of the channel. This mechanical coupling can be tight or loose depending on the channel type, which influences the physiological function of the ion channel. The coupling is not necessarily a direct structural link, other factors, eg.: the lipid content of the given cell membrane could influence the mechanical coupling between the VSD and PD.Voltage-clamp fluorometry (VCF) allows tracking of the movement of the VSD, and measurement of the ionic currents in voltage gated channels simultaneously. Using VCF we can collect information about the individual transitions of the VSD and PD learn about the coupling between the two domains.Major part of the VSD faces membrane lipids which suggest that changes in the lipid composition can modify the coupling and gating mechanisms of the ion channels. Changes in the membrane cholesterol content have been described to affect the biophysical parameters of ion channels, such as conductance, open probability and gating transistions.By modifying membrane cholesterol content we observed changes in VSD and PD function. We performed our experiments with cholesterol and a cholesterol analogue, and also tested voltage gated potassium (Kv) channels from various families to determine the specificity of the observed effects.Project number: KTIANAP13B_2ABB813