An alanine residue in the M3-M4 linker lines the glycine binding pocket of the N-methyl-D-aspartate receptor.
While attempting to map a central region in the M3-M4 linker of the N-methyl-D-aspartate receptor NR1 subunit, we found that mutation of a single position, Ala-714, greatly reduced the apparent affinity for glycine. Proximal N-glycosylation localized this region to the extracellular space. Glycine affinities of additional Ala-714 mutations correlated with side chain volume. Substitution of alanine 714 with cysteine did not alter glycine sensitivity, although this mutant was rapidly inhibited by dithionitrobenzoate. Glycine protected the A714C mutant from modification by dithionitrobenzoate, whereas the co-agonist L-glutamate was ineffective. These experiments place Ala-714 in the glycine binding pocket of the N-methyl-D-aspartate receptor, a determination not predicted by previous structural models based on bacterial periplasmic binding protein homology.
Wood
M W
MW
Department of Pharmacology, Duke University, Durham, North Carolina 27710, USA.
VanDongen
H M
HM
VanDongen
A M
AM
D000409:Alanine / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D005998:Glycine / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000737:chemistry; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D014981:Xenopus
D016194:Receptors, N-Methyl-D-Aspartate; D004228:Dithionitrobenzoic Acid; D017868:Cyclic AMP-Dependent Protein Kinases; D000409:Alanine; D005998:Glycine