3HR6:
reference: The Corynebacterium diphtheriae shaft pilin SpaA is built of tandem Ig-like modules with stabilizing isopeptide and disulfide bonds., Kang HJ, Paterson NG, Gaspar AH, Ton-That H, Baker EN, Proc Natl Acad Sci U S A. 2009 Oct 6;106(40):16967-71. Epub 2009 Sep 21. PMID: 19805181

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