Ion channel evolution

Electrophysiological studies indicate that ion channels are present throughout the animal kingdom. Between distantly-related phyla, similarities in ion selectivity, gating, pharmacology and kinetics have obscured insights into how these proteins might have evolved. Moreover, deduced structures of a limited number of chordate and arthropod ion channels have shown that functionally disparate channel types often share a common structure. At least six different superfamilies of structurally-related ion channels have been described thus far, providing some clues for 'ancestral' proteins of a specific family. By contrast, evolutionary links (should they exist) among these superfamilies are less clear, requiring further structural analysis of ion channels in lower invertebrates, single-celled organisms and plants.