4APW:
reference: Novel Actin-like Filament Structure from Clostridium tetani., Popp D, Narita A, Lee LJ, Ghoshdastider U, Xue B, Srinivasan R, Balasubramanian MK, Tanaka T, Robinson RC, J Biol Chem. 2012 Jun 15;287(25):21121-9. Epub 2012 Apr 18. PMID: 22514279

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