Fig. 1: NMDAR domain organization and ligands.
From: Structural basis of subtype-selective competitive antagonism for GluN2C/2D-containing NMDA receptors
a GluN1/GluN2 form tetrameric receptors with two GluN1 (dark gray) and two GluN2 (light gray) subunits. Each subunit has an ATD, LBD, TMD, and CTD domain (CTD not included). The LBD layer contains a dimer of GluN1–GluN2 heterodimers, one of which is highlighted by a surrounding red dashed line. The GluN1 upper lobe (D1) and lower lobe (D2) are colored in green and orange, and the GluN2 D1 and D2 in purple and magenta. The surface presentation is produced from the PDB structure 4PE5. b Schematic representation of GluN1 and GluN2 subunits. Glycine, l-glutamate, and competitive antagonists bind in the LBD clefts. The modular build of the subunits allows isolation of the GluN1 and GluN2A LBDs by replacing the M1–M3 transmembrane sequence with a Gly-Thr dipeptide linker. Color coding as in (a). c Chemical structures of GluN2 agonists L-glutamate and homoquinolinic acid and antagonists PPDA and UBP791 at pH ~7. PPDA and UBP791 are cis-racemic mixtures of (2S,3R)- and (2R,3S)-isomers.
