1XHF:
reference: Structural Analysis and Solution Studies of the Activated Regulatory Domain of the Response Regulator ArcA: A Symmetric Dimer Mediated by the alpha4-beta5-alpha5 Face., Toro-Roman A, Mack TR, Stock AM, J Mol Biol 2005 May 27;349(1):11-26. Epub 2005 Apr 7. PMID: 15876365

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