Binding of ArgTX-636 in the NMDA receptor ion channel

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The N-methyl-d-aspartate receptors (NMDARs) constitute an important class of ligand-gated cation channels that are involved in the majority of excitatory neurotransmission in the human brain. Compounds that bind in the NMDAR ion channel and act as blockers are use- and voltage-dependent inhibitors of NMDAR activity and have therapeutic potential for treatment of a variety of brain diseases or as pharmacological tools for studies of the neurobiological role of NMDARs. We have performed a kinetic analysis of the blocking mechanism of the prototypical polyamine toxin NMDAR ion channel blocker argiotoxin-636 (ArgTX-636) at recombinant GluN1/2A receptors to provide detailed information on the mechanism of block. The predicted binding site of ArgTX-636 is in the pore region of the NMDAR ion channel formed by residues in the transmembrane M3 and the M2 pore-loop segments of the GluN1 and GluN2A subunits. To assess the predicted binding mode in further detail, we performed an alanine- and glycine-scanning mutational analysis of this pore-loop segment to systematically probe the role of pore-lining M2 residues in GluN1 and GluN2A in the channel block by ArgTX-636. Comparison of M2 positions in GluN1 and GluN2A where mutation influences ArgTX-636 potency suggests differential contribution of the M2-loops of GluN1 and GluN2A to binding of ArgTX-636. The results of the mutational analysis are highly relevant for the future structure-based development of argiotoxin-derived NMDAR channel blockers.

Original languageEnglish
JournalJournal of Molecular Biology
Issue number1
Pages (from-to)176-89
Number of pages14
Publication statusPublished - 16 Jan 2015

    Research areas

  • Animals, Binding Sites, Electrophysiology, Glutamic Acid, HEK293 Cells, Humans, Indoleacetic Acids, Ion Channels, Kinetics, Models, Molecular, Mutagenesis, Mutation, Patch-Clamp Techniques, Polyamines, Protein Conformation, Protein Subunits, Rats, Receptors, N-Methyl-D-Aspartate, Recombinant Fusion Proteins, Spider Venoms

ID: 138769639