4M57:
reference: Structural basis for the modular recognition of single-stranded RNA by PPR proteins., Yin P, Li Q, Yan C, Liu Y, Liu J, Yu F, Wang Z, Long J, He J, Wang HW, Wang J, Zhu JK, Shi Y, Yan N, Nature. 2013 Oct 27. doi: 10.1038/nature12651. PMID: 24162847

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