3T1E:
reference: Structure of the Newcastle disease virus hemagglutinin-neuraminidase (HN) ectodomain reveals a four-helix bundle stalk., Yuan P, Swanson KA, Leser GP, Paterson RG, Lamb RA, Jardetzky TS, Proc Natl Acad Sci U S A. 2011 Sep 6;108(36):14920-5. Epub 2011 Aug 22. PMID: 21873198

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