5KA5:
reference: Receptor Activation of HIV-1 Env Leads to Asymmetric Exposure of the gp41 Trimer., Khasnis MD, Halkidis K, Bhardwaj A, Root MJ, PLoS Pathog. 2016 Dec 19;12(12):e1006098. doi: 10.1371/journal.ppat.1006098., eCollection 2016 Dec. PMID: 27992602

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