4TWD:
reference: The Prokaryote Ligand-Gated Ion Channel ELIC Captured in a Pore Blocker-Bound Conformation by the Alzheimer's Disease Drug Memantine., Ulens C, Spurny R, Thompson AJ, Alqazzaz M, Debaveye S, Han L, Price K, Villalgordo JM, Tresadern G, Lynch JW, Lummis SC, Structure. 2014 Sep 3. pii: S0969-2126(14)00244-5. doi:, 10.1016/j.str.2014.07.013. PMID: 25199693

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