6I2T:
reference: Cryo-EM structure of the native butyrylcholinesterase tetramer reveals a dimer of dimers stabilized by a superhelical assembly., Leung MR, van Bezouwen LS, Schopfer LM, Sussman JL, Silman I, Lockridge O, Zeev-Ben-Mordehai T, Proc Natl Acad Sci U S A. 2018 Dec 11. pii: 1817009115. doi:, 10.1073/pnas.1817009115. PMID: 30538207

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