3FWE:
reference: Structure of apo-CAP reveals that large conformational changes are necessary for DNA binding., Sharma H, Yu S, Kong J, Wang J, Steitz TA, Proc Natl Acad Sci U S A. 2009 Sep 29;106(39):16604-9. Epub 2009 Sep 16. PMID: 19805344

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