2BC3:
reference: Crystallographic Analysis of a Full-length Streptavidin with Its C-terminal Polypeptide Bound in the Biotin Binding Site., Le Trong I, Humbert N, Ward TR, Stenkamp RE, J Mol Biol. 2006 Feb 24;356(3):738-45. Epub 2005 Dec 15. PMID: 16384581

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