2LIG:
reference: Three-dimensional structures of the ligand-binding domain of the bacterial aspartate receptor with and without a ligand., Milburn MV, Prive GG, Milligan DL, Scott WG, Yeh J, Jancarik J, Koshland DE Jr, Kim SH, Science 1991 Nov 29;254(5036):1342-7. PMID: 1660187

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