3GQH:
reference: Crystallographic insights into the autocatalytic assembly mechanism of a bacteriophage tail spike., Xiang Y, Leiman PG, Li L, Grimes S, Anderson DL, Rossmann MG, Mol Cell. 2009 May 15;34(3):375-86. PMID: 19450535

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