4TLM:
reference: NMDA receptor structures reveal subunit arrangement and pore architecture., Lee CH, Lu W, Michel JC, Goehring A, Du J, Song X, Gouaux E, Nature. 2014 Jul 10;511(7508):191-7. doi: 10.1038/nature13548. Epub 2014 Jun 22. PMID: 25008524

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).