Mapping convulsants' binding to the GABA-A receptor chloride ionophore: a proposed model for channel binding sites.
Gamma-aminobutyric acid (GABA) type A receptors play a key role in brain inhibitory neurotransmission, and are ligand-activated chloride channels blocked by numerous convulsant ligands. Here we summarize data on binding of picrotoxin, tetrazoles, beta-lactams, bicyclophosphates, butyrolactones and neurotoxic pesticides to GABA-A ionophore, and discuss functional and structural overlapping of their binding sites. The paper reviews data on convulsants' binding sensitivity to different point mutations in ionophore-lining second trans-membrane domains of GABA-A subunits, and maps possible location of convulsants' sites within the chloride ionophore. We also discuss data on inhibition of glycine, glutamate, serotonin (5-HT3) and N-acetylcholine receptors by GABA-A channel blockers, and examine the applicability of this model to other homologous ionotropic receptors. Positioning various convulsant-binding sites within ionophore of GABA-A receptors, this model enables a better understanding of complex architectonics of ionotropic receptors, and may be used for developing new channel-modulating drugs.
Kalueff
A V
AV
Laboratory of Clinical Science, Building 10, Room 3D41, National Institute of Mental Health (NIMH), NIH, 10 Center Dr. MSC 1264, Bethesda, MD 20892-1264, USA. kalueva@mail.nih.gov
D000818:Animals; D001665:Binding Sites; D003292:Convulsants / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D011963:Receptors, GABA-A / Q000378:metabolism*
D003292:Convulsants; D008024:Ligands; D011963:Receptors, GABA-A