6GHJ:
reference: Tripeptide binding in a Proton-Dependent Oligopeptide Transporter., Martinez Molledo M, Quistgaard EM, Low C, FEBS Lett. 2018 Sep 8. doi: 10.1002/1873-3468.13246. PMID: 30194725

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