2C4R:
reference: Structure of Escherichia coli RNase E catalytic domain and implications for RNA turnover., Callaghan AJ, Marcaida MJ, Stead JA, McDowall KJ, Scott WG, Luisi BF, Nature. 2005 Oct 20;437(7062):1187-91. PMID: 16237448

This OCA Structure page
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