4RZD:
reference: Structural analysis of a class III preQ1 riboswitch reveals an aptamer distant from a ribosome-binding site regulated by fast dynamics., Liberman JA, Suddala KC, Aytenfisu A, Chan D, Belashov IA, Salim M, Mathews DH, Spitale RC, Walter NG, Wedekind JE, Proc Natl Acad Sci U S A. 2015 Jun 23. pii: 201503955. PMID: 26106162

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