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. 2015 Jan 9;115(6):2453–2481. doi: 10.1021/cr5004248

Figure 12.

Figure 12

The role of PARP-1 as a regulator of polyadenylation during heat shock. (A) Lengthening of the polyadenylated 3′ end of an mRNA is associated with endonucleolytic cleavage of pre-mRNAs catalyzed by CPSF73, which recognizes the highly conserved AAUAAA hexamer, followed by the synthesis of a poly(A) tail onto the 5′ cleaved product by PAP under normal conditions.93,222 (B) PARP-1 activation by heat shock inhibits generation of the poly(A) tail by PARylation of the PAP, which is associated with significant inhibition of polyadenylation activity. PARylated PAP loses its ability to bind to the 3′ end of mRNA precursors, which subsequently arrests gene expression. The arrow represents the cleavage site.93,222