3QE4:
reference: An Evolved Aminoacyl-tRNA Synthetase with Atypical Polysubstrate Specificity ., Young DD, Young TS, Jahnz M, Ahmad I, Spraggon G, Schultz PG, Biochemistry. 2011 Feb 1. PMID: 21280675

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