Poly(A) nuclease interacts with the c-terminal domain of polyadenylate-binding protein domain from poly(A)-binding protein

The poly( A)- binding protein ( PABP) is an essential protein found in all eukaryotes and is involved in an extensive range of cellular functions, including translation, mRNA metabolism, and mRNA export. Its C- terminal region contains a peptideinteracting PABC domain that recruits proteins containing a highly specific PAM- 2 sequence motif to the messenger ribonucleoprotein complex. In humans, these proteins, including Paip1, Paip2, eRF3 ( eukaryotic release factor 3), Ataxin-2, and Tob2, are all found to regulate translation through varying mechanisms. The following reports poly( A) nuclease ( PAN) as a PABC-interacting partner in both yeast and humans. Their interaction is mediated by a PAM- 2 motif identified within the PAN3 subunit. This site was identified in various fungal and animal species suggesting that the interaction is conserved throughout evolution. Our results indicate that PABP is directly involved in recruiting a deadenylase to the messenger ribonucleoprotein complex. This demonstrates a novel role for the PABC domain in mRNA metabolic processes and gives further insight into the function of PABP in mRNA maturation, export, and turnover.