An ionophore is a lipid-soluble molecule usually synthesized by microorganisms to transport ions across the lipid bilayer of the cell membrane. The two broad classifications of ionophores are:
Chemical compounds (mobile ion carriers) that bind to a particular ion,[1] shielding its charge from the surrounding environment, and thus facilitating its crossing of the hydrophobic interior of the lipid membrane
Channel formers[2] that introduce a hydrophilic pore into the membrane, allowing ions to pass through while avoiding contact with the membrane's hydrophobic interior