1UET:
reference: Divergent evolutions of trinucleotide polymerization revealed by an archaeal CCA-adding enzyme structure., Okabe M, Tomita K, Ishitani R, Ishii R, Takeuchi N, Arisaka F, Nureki O, Yokoyama S, EMBO J 2003 Nov 3;22(21):5918-27. PMID: 14592988

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