Characterisation of the human NMDA receptor subunit NR3A glycine binding site

A Nilsson, J Duan, L-L Mo-Boquist, Eirikur Benedikz, E Sundström

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

In this study, we characterise the binding site of the human N-methyl-d-aspartate (NMDA) receptor subunit NR3A. Saturation radioligand binding of the NMDA receptor agonists [(3)H]-glycine and [(3)H]-glutamate showed that only glycine binds to human NR3A (hNR3A) with high affinity (K(d)=535nM (277-793nM)). Eight amino acids, which correspond to amino acids that are critical for ligand binding to other NMDA receptor subunits, situated within the S1S2 predicted ligand binding domain of hNR3A were mutated, which resulted in complete or near complete loss of [(3)H]-glycine binding to hNR3A. The NMDA NR1 glycine site agonist d-serine and partial agonist HA-966 (3-amino-1-hydroxypyrrolid-2-one), similarly to glycine displaced [(3)H]-glycine monophasically, suggesting a single common binding site. However, neither the partial agonist d-cycloserine nor the antagonist 7-chlorokynurenic acid displaced [(3)H]-glycine. Using homology modelling, a model of the NR3A binding pocket was generated which we suggest can be used to identify candidate agonists and antagonists. Our data show that glycine is a ligand, and most probably the endogenous ligand, for native NR3A at a binding site with unique pharmacological characteristics.
Original languageEnglish
JournalNeuropharmacology
Volume52
Issue number4
Pages (from-to)1151-9
Number of pages9
ISSN0028-3908
DOIs
Publication statusPublished - 2007

Keywords

  • Animals
  • Binding, Competitive
  • Brain
  • Cell Line, Transformed
  • Cycloserine
  • Dose-Response Relationship, Drug
  • Excitatory Amino Acid Antagonists
  • Glycine
  • Humans
  • Kynurenic Acid
  • Models, Molecular
  • Mutation
  • Protein Binding
  • Rats
  • Receptors, N-Methyl-D-Aspartate
  • Transfection

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