FUNCTIONAL DOMAINS OF GABA(A) RECEPTORS

The transmitter-gated ion channels mediate rapid synaptic transmission, for exam pie, at the neuromuscular junction using acetylcholine and in the CNS using primarily the amino acids glutamate and GABA. GABA(A)-receptor Cl- channels share sequence homology with a superfamily of these channels including nicotinic acetylcholine receptor and inhibitory glycine receptor. In this article, Geoffrey Smith and Richard Risen discuss recent affinity labelling and site-directed mutagenesis studies on GABA(A) receptors that have identified amino acid residues essential for binding of agonists and allosteric modulators as well as the ion channel wall formation. The structural domains identified are consistent with results obtained with other members of the transmitter-gated ion channel superfamily and suggest that structural mod els for one member of the family may apply to the others as well.