3RWN:
reference: Atomic structure of bacteriophage Sf6 tail needle knob., Bhardwaj A, Molineux IJ, Casjens SR, Cingolani G, J Biol Chem. 2011 Jun 25. PMID: 21705802

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