5FRX:
reference: Structural Analysis of the Phenol-Responsive Sensory Domain of the Transcription Activator PoxR., Patil VV, Park KH, Lee SG, Woo E, Structure. 2016 Apr 5;24(4):624-30. doi: 10.1016/j.str.2016.03.006. PMID: 27050690

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