6W0A:
reference: Open and Closed Structures of a Barium-Blocked Potassium Channel., Rohaim A, Gong L, Li J, Rui H, Blachowicz L, Roux B, J Mol Biol. 2020 Aug 7;432(17):4783-4798. doi: 10.1016/j.jmb.2020.06.012. Epub, 2020 Jun 29. PMID: 32615129

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