3IQM:
reference: ATPase Active-Site Electrostatic Interactions Control the Global Conformation of the 100 kDa SecA Translocase., Kim DM, Zheng H, Huang YJ, Montelione GT, Hunt JF, J Am Chem Soc. 2013 Feb 27;135(8):2999-3010. doi: 10.1021/ja306361q. Epub 2013, Feb 14. PMID: 23167435

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