1I9B:
reference: Crystal structure of an ACh-binding protein reveals the ligand-binding domain of nicotinic receptors., Brejc K, van Dijk WJ, Klaassen RV, Schuurmans M, van Der Oost J, Smit AB, Sixma TK, Nature 2001 May 17;411(6835):269-76. PMID: 11357122

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