title: Antagonism of ligand-gated ion channel receptors: two domains of the glycine receptor alpha subunit form the strychnine-binding site.
abstract: The inhibitory glycine receptor (GlyR) is a member of the ligand-gated ion channel receptor superfamily. Glycine activation of the receptor is antagonized by the convulsant alkaloid strychnine. Using in vitro mutagenesis and functional analysis of the cDNA encoding the alpha 1 subunit of the human GlyR, we have identified several amino acid residues that form the strychnine-binding site. These residues were identified by transient expression of mutated cDNAs in mammalian (293) cells and examination of resultant [3H]strychnine binding, glycine displacement of [3H]strychnine, and electrophysiological responses to the application of glycine and strychnine. This mutational analysis revealed that residues from two separate domains within the alpha 1 subunit form the binding site for the antagonist strychnine. The first domain includes the amino acid residues Gly-160 and Tyr-161, and the second domain includes the residues Lys-200 and Tyr-202. These results, combined with analyses of other ligand-gated ion channel receptors, suggest a conserved tertiary structure and a common mechanism for antagonism in this receptor superfamily.
authors.affiliation: Neurobiology Division, Garvan Institute of Medical Research, Darlinghurst, N.S.W., Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Vandenberg
authors.forename: C R
authors.initials: CR
authors.lastname: French
authors.forename: P H
authors.initials: PH
authors.lastname: Barry
authors.forename: J
authors.initials: J
authors.lastname: Shine
authors.forename: P R
authors.initials: PR
authors.lastname: Schofield
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D005998:Glycine / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D018009:Receptors, Glycine; D017981:Receptors, Neurotransmitter / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D013331:Strychnine / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry
chemical_list: D018009:Receptors, Glycine; D017981:Receptors, Neurotransmitter; D011994:Recombinant Proteins; D014443:Tyrosine; D013331:Strychnine; D008239:Lysine; D005998:Glycine