5C2N:
reference: De Novo Evolutionary Emergence of a Symmetrical Protein Is Shaped by Folding Constraints., Smock RG, Yadid I, Dym O, Clarke J, Tawfik DS, Cell. 2016 Jan 28;164(3):476-86. doi: 10.1016/j.cell.2015.12.024. Epub 2016 Jan, 21. PMID: 26806127

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