The benzodiazepine binding site of GABA(A) receptors

The GABA(A) receptor belongs, along with the nicotinic acetylcholine receptor, the glycine receptor and the 5-HT3 receptor, to a family of homologous transmitter gated ion chann els mediating fast synaptic transmission. Many classes of drug interact with the GABA(A) receptor, which is the major inhibitory ion channel in the mammalian brain. Among these drugs are the allosteric modulators acting at the benzodiazepine binding site. In this article, Erwin Sigel and Andreas Buhr discuss recent studies that have identified amino acid residues that are thought to form the binding pocket for these compounds. These residues are probably located at subunit interfaces of the protein pentamer and at least some of them are homologous to residues implicated in channel agonist binding. This implies pseudosymmetry of channel agonist and channel modulatory sites, which may be, as recent data indicate, a general principle realized in other pseudosymmetric protein complexes.