6SSP:
reference: Modulation of the Erwinia ligand-gated ion channel (ELIC) and the 5-HT3 receptor via a common vestibule site., Brams M, Govaerts C, Kambara K, Price KL, Spurny R, Gharpure A, Pardon E, Evans GL, Bertrand D, Lummis SC, Hibbs RE, Steyaert J, Ulens C, Elife. 2020 Jan 28;9. pii: 51511. doi: 10.7554/eLife.51511. PMID: 31990273

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