2LO6:
reference: Serine phosphorylation and proline isomerization in RNAP II CTD control recruitment of Nrd1., Kubicek K, Cerna H, Holub P, Pasulka J, Hrossova D, Loehr F, Hofr C, Vanacova S, Stefl R, Genes Dev. 2012 Sep 1;26(17):1891-6. doi: 10.1101/gad.192781.112. Epub 2012 Aug, 14. PMID: 22892239

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