2GWR:
reference: Domain orientation in the inactive response regulator Mycobacterium tuberculosis MtrA provides a barrier to activation., Friedland N, Mack TR, Yu M, Hung LW, Terwilliger TC, Waldo GS, Stock AM, Biochemistry. 2007 Jun 12;46(23):6733-43. Epub 2007 May 19. PMID: 17511470

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