Valinomycin–mediated Cation Transport in Planar Bilayer Lipid Membranes

Valinomycin is a natural dodecadepsipetide ionophore largely used for selective K+ transport across artificial and natural lipid membranes, and as an antibiotic. As a transporter, valinomycin passively moves K+ ions across membrane down the electrochemical gradient. It is well known that valinomycin selectivity for K+ is ~ 100,000 greater then the selectivity measured for Na+, which makes the carrier an excellent tool for exploring transport phenomena in living cells, where the ions are major cations. However, little is known about valinomycin’s capability to transport other monovalent cations, or how the lipid composition of the target membrane affect membrane binding and transport properties. Therefore, our studies focused on understanding the valinomycin’s transport properties in artificial membrane systems comprising planar lipid membranes and electrophysiology measurements.