1FQF:
reference: Crystal structures and iron release properties of mutants (K206A and K296A) that abolish the dilysine interaction in the N-lobe of human transferrin., Nurizzo D, Baker HM, He QY, MacGillivray RT, Mason AB, Woodworth RC, Baker EN, Biochemistry 2001 Feb 13;40(6):1616-23. PMID: 11327820

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