3VN9:
reference: Crystal structure of non-phosphorylated MAP2K6 in a putative auto-inhibition state., Matsumoto T, Kinoshita T, Matsuzaka H, Nakai R, Kirii Y, Yokota K, Tada T, J Biochem. 2012 May;151(5):541-9. Epub 2012 Mar 1. PMID: 22383536

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