4IRE:
reference: Signal transduction pathways in the pentameric ligand-gated ion channels., Mowrey D, Chen Q, Liang Y, Liang J, Xu Y, Tang P, PLoS One. 2013 May 8;8(5):e64326. doi: 10.1371/journal.pone.0064326. Print 2013. PMID: 23667707

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