3RKP:
reference: Isopeptide bonds of the major pilin protein BcpA influence pilus structure and bundle formation on the surface of Bacillus cereus., Hendrickx AP, Poor CB, Jureller JE, Budzik JM, He C, Schneewind O, Mol Microbiol. 2012 Jul;85(1):152-63. doi: 10.1111/j.1365-2958.2012.08098.x. Epub, 2012 Jun 1. PMID: 22624947

This OCA Structure page
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