6C9W:
reference: Crystal Structure of a ligand-bound LacY-Nanobody Complex., Kumar H, Finer-Moore JS, Jiang X, Smirnova I, Kasho V, Pardon E, Steyaert J, Kaback HR, Stroud RM, Proc Natl Acad Sci U S A. 2018 Aug 14. pii: 1801774115. doi:, 10.1073/pnas.1801774115. PMID: 30108145

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