title: Ion transport across biological membranes. Diffusion in water solution or conduction in the solid state?
abstract: The mechanism of the highly efficient and precisely regulated ion flux across axonal membranes has usually been considered as free diffusion in aqueous channels. The evidence for single-file mechanisms has not been convincing. In this report, solid-state ionic conductance is proposed as an alternative mechanism. The sequence of the Na+ 'channel' protein is scrutinized for elements that may form an ionic core that is well insulated by a hydrophobic mantle from other segments of the protein. A specific structure is proposed that may correspond to ionic lattices as they are known to exist in crystals of small, inorganic electrolytes that exhibit considerable ionic conduction.
mesh_terms: D001369:Axons / Q000648:ultrastructure; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D004058:Diffusion; D004553:Electric Conductivity; D007473:Ion Channels / Q000378:metabolism; D007477:Ions / Q000378:metabolism*; D008954:Models, Biological; D011487:Protein Conformation; D012964:Sodium / Q000378:metabolism; D012996:Solutions; D014867:Water
chemical_list: D007473:Ion Channels; D007477:Ions; D012996:Solutions; D014867:Water; D012964:Sodium