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. Author manuscript; available in PMC: 2019 May 1.
Published in final edited form as: Adv Biol Regul. 2017 Aug 24;68:107–119. doi: 10.1016/j.jbior.2017.08.002

Figure 4. The 3’-mRNA exonuclease PARN.

Figure 4

(A) Modular scheme of the PARN protein. The PARN protein consists of three distinct exonuclease (deadenylase) sites (Exo I, Exo II, and Exo III) contained in two nuclease regions also with two RNA binding regions (R3H and RRM). (B) PARN targets mRNA 3' UTR containing long stretches of AU combinations called, AU- rich elements (AREs). Such elements are present in the 3' UTR of pLD1 mRNA. (C) PARN contributes to mRNA degradation through the cleavage of mRNA poly(A) tails (deadenylase function) followed by decapping and by exonuclease activity; cleaved mRNAs accumulate in “P bodies” in the cell that can be observed under the microscope.