6DKK:
reference: A viral-fusion-peptide-like molecular switch drives membrane insertion of botulinum neurotoxin A1., Lam KH, Guo Z, Krez N, Matsui T, Perry K, Weisemann J, Rummel A, Bowen ME, Jin R, Nat Commun. 2018 Dec 18;9(1):5367. doi: 10.1038/s41467-018-07789-4. PMID: 30560862

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