1ORC:
reference: High-resolution structure of an engineered Cro monomer shows changes in conformation relative to the native dimer., Albright RA, Mossing MC, Matthews BW, Biochemistry 1996 Jan 23;35(3):735-42. PMID: 8547253

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