4FFB:
reference: A TOG:alphabeta-tubulin complex structure reveals conformation-based mechanisms for a microtubule polymerase., Ayaz P, Ye X, Huddleston P, Brautigam CA, Rice LM, Science. 2012 Aug 17;337(6096):857-60. PMID: 22904013

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