Molecular Crowding Affects the Functionality of Voltage-gated Channels

Cell membranes are biological structures packed with proteins so that the biological activity of membrane proteins is exerted in a crowded environment. Membrane inventories of typical biological membranes indicate protein to lipid mass ratios of order 1-2.5, hence the propensity for naturally-occurring crowding conditions. In addition, the confinement of the membrane in a two-dimensional assembly further contributes in achieving crowding conditions in the membrane plane rather than a three-dimensional distribution. Very often, studies of biological functionality and biophysical characterizations of membrane proteins are carried out under “dilute” conditions to minimize the potential non-specific interactions. The influence of crowding on the functionality of membrane proteins in general is addressed in multiple models and theoretical simulations that suggest dramatic changes in the functionality of membrane proteins upon crowding. Nevertheless, experimental evidence of crowding effects on the functionality of packed membrane proteins is sparse and much less extended than similar studies on proteins crowded in a cytosol-like environment. The work herein elucidate the changes in the dynamics of voltage-gated channels in crowding conditions experimentally achieved by modulating the density of the channels inserted into an artificial Bilayer Lipid Membrane. We concluded that crowding induces major changes in the energy landscape most probably by long-range inter-channel interactions.