4RUR:
reference: Indolo-Phakellins as beta5-Specific Noncovalent Proteasome Inhibitors., Beck P, Lansdell TA, Hewlett NM, Tepe JJ, Groll M, Angew Chem Int Ed Engl. 2015 Jan 7. doi: 10.1002/anie.201410168. PMID: 25581903

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