4Y52:
reference: Molecular basis for 5-carboxycytosine recognition by RNA polymerase II elongation complex., Wang L, Zhou Y, Xu L, Xiao R, Lu X, Chen L, Chong J, Li H, He C, Fu XD, Wang D, Nature. 2015 Jun 29. doi: 10.1038/nature14482. PMID: 26123024

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