| 1PFB: reference: Structural basis for specific binding of Polycomb chromodomain to histone H3 methylated at Lys 27., Min J, Zhang Y, Xu RM, Genes Dev 2003 Aug 1;17(15):1823-8. PMID: 12897052 |
This OCA 
Structure page
uses Jmol,
developed by the Jmol Development Team
(documentation).