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Updated: May 22, 2026

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Novel interactions at the essential N-terminus of poly(A) polymerase that could regulate poly(A) addition in
Chukwudi Ezeokonkwo1, Mohamed A Ghazy, Alexander Zhelkovsky
1Tufts School of Medicine and the Sackler Graduate School of Biomedical Sciences, Boston, MA 02111, USA.
Abstract:
Addition of poly(A) to the 3' ends of cleaved pre-mRNA is essential for mRNA maturation and is catalyzed by Pap1 in yeast. We have previously shown that a non-viable Pap1 mutant lacking the first 18 amino acids is fully active for polyadenylation of oligoA, but defective for pre-mRNA polyadenylation, suggesting that interactions at the N-terminus are important for enzyme function in the processing complex. We have now identified proteins that interact specifically with this region. Cft1 and Pta1 are subunits of the cleavage/polyadenylation factor, in which Pap1 resides, and Nab6 and Sub1 are nucleic-acid binding proteins with known links to 3' end processing. Our results suggest a novel mechanism for controlling Pap1 activity, and possible models invoking these newly-discovered interactions are discussed.
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