3R1F:
reference: EspR, a key regulator of Mycobacterium tuberculosis virulence, adopts a unique dimeric structure among helix-turn-helix proteins., Rosenberg OS, Dovey C, Tempesta M, Robbins RA, Finer-Moore JS, Stroud RM, Cox JS, Proc Natl Acad Sci U S A. 2011 Jul 27. PMID: 21795602

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