1D1L:
reference: The structural basis for enhanced stability and reduced DNA binding seen in engineered second-generation Cro monomers and dimers., Rupert PB, Mollah AK, Mossing MC, Matthews BW, J Mol Biol 2000 Mar 3;296(4):1079-90. PMID: 10686105

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