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. Author manuscript; available in PMC: 2017 Jul 1.
Published in final edited form as: Trends Mol Med. 2016 Jun 3;22(7):615–628. doi: 10.1016/j.molmed.2016.05.005

Figure 2. Competition Between hTR RNP Assembly and Quality Control.

Figure 2

Under normal conditions, hTR is bound by dyskerin and other H/ACA proteins to form the hTR RNP. In DC, unassembled hTR is degraded by EXOSC10 in the nucleus, and by DCP2/XRN1 in the cytoplasm. DCP2 removes the m7Gpp cap structure from the 5’ end of hTR, exposing the monophosphate to allow XRN1-mediated exonucleolytic digestion. Loss of PARN also leads to degradation of hTR by EXOSC10, which is aided by PAPD5-mediated oligoadenylation of hTR 3’ end, where it can destabilize both unbound and assembled hTR molecules.