3HOL:
reference: Insights into the bacterial transferrin receptor: the structure of transferrin-binding protein B from Actinobacillus pleuropneumoniae., Moraes TF, Yu RH, Strynadka NC, Schryvers AB, Mol Cell. 2009 Aug 28;35(4):523-33. PMID: 19716795

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