Structural aspects of ionophore function.

Ionophores increase permeability in lipid bilayer membranes by two different mechanisms. Pores are relatively long-lasting, stationary structures that allow the passage of a large number of ions during their existence. Carriers, in contrast, move through the membrane in association with individual ions. Changes in the lipid composition of the membrane affect the two permeation mechanisms differently. The relationship between membrane structure and ion permeability is analyzed by considering the membrane interior and the region of polar headgroups separately.