1CRX:
reference: Structure of Cre recombinase complexed with DNA in a site-specific recombination synapse., Guo F, Gopaul DN, van Duyne GD, Nature 1997 Sep 4;389(6646):40-6. PMID: 9288963

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