Architecture of receptor-operated ion channels of biological membranes

Ion channels of biological membranes are the key proteins that provide for bioelectric functioning of living systems. These proteins are homo- or heterooligomers assembled of several identical or different subunits. Understanding the architectural organization and functioning of ion channels has significantly expanded owing to resolving the crystal structure of several types of voltage-gated and receptor-operated channels. This review summarizes the information obtained from crystal structures of potassium channels, nicotinic acetylcholine receptor, ATP-activated, and other ligand-gated ion channels. Despite the differences in the function, topology, ion selectivity, and subunit stoichiometry, a high similarity in the principles of organization of these macromolecular complexes has been revealed.