2WII:
reference: Structure of complement fragment C3b-factor H and implications for host protection by complement regulators., Wu J, Wu YQ, Ricklin D, Janssen BJ, Lambris JD, Gros P, Nat Immunol. 2009 Jul;10(7):728-33. Epub 2009 Jun 7. PMID: 19503104

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