Polyadenylate-binding protein 2

Polyadenylate-binding protein 2 (PABPN1) is a nuclear RNA-binding protein that regulates 3'-end formation of mRNA precursors by stimulating poly(A) tail elongation and controlling tail length (UniProt: Q86U42). It functions throughout mRNA metabolism, including nucleocytoplasmic trafficking and nonsense-mediated decay, and is a component of the poly(A) tail exosome targeting (PAXT) complex that directs certain RNAs for degradation. PABPN1 mutations cause oculopharyngeal muscular dystrophy 1 (OPMD1), an autosomal dominant late-onset myopathy affecting eye and throat muscles (UniProt: Q86U42).

PABPN1 is upregulated in Alzheimer's disease brain tissue, showing a mean log2 fold-change of 1.17 in post-mortem AD brain compared to age-matched controls across subcellular fractions (Chaparral AD proteomics). This elevation may reflect altered mRNA stability and decay pathways in the context of neurodegeneration, though the functional consequences remain to be elucidated.