4X2Y:
reference: Structure determination of Murine Norovirus NS6 proteases with C-terminal extensions designed to probe protease-substrate interactions., Fernandes H, Leen EN, Cromwell H Jr, Pfeil MP, Curry S, PeerJ. 2015 Feb 26;3:e798. doi: 10.7717/peerj.798. eCollection 2015. PMID: 25755927

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