5TCS:
reference: Conserved Tetramer Junction in the Kinetochore Ndc80 Complex., Valverde R, Ingram J, Harrison SC, Cell Rep. 2016 Nov 15;17(8):1915-1922. doi: 10.1016/j.celrep.2016.10.065. PMID: 27851957

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