4PHC:
reference: Comparison of histidine recognition in human and trypanosomatid histidyl-tRNA synthetases., Koh CY, Wetzel AB, de van der Schueren WJ, Hol WG, Biochimie. 2014 Nov;106:111-20. doi: 10.1016/j.biochi.2014.08.005. Epub 2014 Aug , 20. PMID: 25151410

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