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. Author manuscript; available in PMC: 2015 Aug 12.
Published in final edited form as: J Mol Biol. 2014 Jun 18;426(16):2970–2981. doi: 10.1016/j.jmb.2014.06.010

Figure 5.

Figure 5

A model for Rtr1’s role in the transcription cycle. Phosphorylation of Ser5 on the CTD at the start of transcription facilitates the recruitment of the mRNA capping complexes (top). As the polymerase moves into elongation and termination modes, the CTD is highly phosphorylated by multiple kinases, including an as of yet identified Tyr1 kinase. Rtr1 becomes active against Ser5P during the elongation phase (bottom) of transcription due to the recognition of an as-of-yet determined CTD code. The Tyr1 marker is heavily phosphorylated during elongation and is also a target for dephosphorylation by Rtr1.