Antagonism of ligand-gated ion channel receptors: two domains of the glycine receptor alpha subunit form the strychnine-binding site.
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.
Vandenberg
R J
RJ
Neurobiology Division, Garvan Institute of Medical Research, Darlinghurst, N.S.W., Australia.
French
C R
CR
Barry
P H
PH
Shine
J
J
Schofield
P R
PR
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
D018009:Receptors, Glycine; D017981:Receptors, Neurotransmitter; D011994:Recombinant Proteins; D014443:Tyrosine; D013331:Strychnine; D008239:Lysine; D005998:Glycine