6J6J:
reference: Single particle cryo-EM reconstruction of 52 kDa streptavidin at 3.2 Angstrom resolution., Fan X, Wang J, Zhang X, Yang Z, Zhang JC, Zhao L, Peng HL, Lei J, Wang HW, Nat Commun. 2019 Jun 3;10(1):2386. doi: 10.1038/s41467-019-10368-w. PMID: 31160591

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