Mo. Ortells et Gg. Lunt, EVOLUTIONARY HISTORY OF THE LIGAND-GATED ION-CHANNEL SUPERFAMILY OF RECEPTORS, Trends in neurosciences, 18(3), 1995, pp. 121-127
The fast-acting ligand-gated ion channels (LGICs) constitute a group t
hat encompasses nicotinic ACh, 5-HT3, GABA(A) and glycine receptors. U
ndoubtedly, they all share a common evolutionary ancestor, and the gro
up can therefore be considered to be a gene superfamily. Because the m
embers of the superfamily are all receptors, it is reasonable to suppo
se that their common ancestor must also have been some type of recepto
r, and because the receptors are made of similar subunits, the ancesto
r was probably homo-oligomeric. Although we failed to find a group of
proteins that are related evolutionarily to this superfamily, the anal
ysis of the evolutionary relationships within the superfamily is possi
ble and can give rise to information about the evolution of the struct
ure and function of present-day receptors and indeed of the nervous sy
stem itself.