Comparison of Ion Selectivity Mechanisms in Bacterial and Mammalian Sodium Channels

Voltage-gated sodium (Nav) channels play essential roles in electrical signalling in the body and are associated with many physiological disorders. The availability of recent high-resolution structures for bacterial Nav channels makes them ideal tools for exploring functional mechanisms. Bacterial and mammalian channels have been proposed to select for Na+ over K+ via different mechanisms, owing to their distinct selectivity signature sequences, with bacterial channels making use of a 4-fold ring of Glu side chains, in place of Asp, Glu, Lys and Ala (DEKA) in mammalian channels.