Defect Structures in Membranes: Routes for the Permeation of Small Molecules

Transient defect structures in thermodynamic equilibrium with the membrane lattice are considered to be major pathways for the passive permeation of small and neutral (with the possible exception of protons) molecules. Results on the water permeation and on the transfer of protons across erythrocyte membranes are discussed. The inhibition/stimulation of transport rates is interpreted in terms of specific or global actions of the inhibitory/stimulatory molecules on lipid/protein and protein/protein assemblies.