3B2M:
reference: Stabilizing isopeptide bonds revealed in gram-positive bacterial pilus structure., Kang HJ, Coulibaly F, Clow F, Proft T, Baker EN, Science. 2007 Dec 7;318(5856):1625-8. PMID: 18063798

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