polyAbinding

polyAbinding refers to the set of molecular interactions by which proteins recognize and bind to polyadenylated RNA, particularly the poly(A) tail that extends from most eukaryotic mRNA. The term encompasses both nuclear and cytoplasmic poly(A)-binding activities, mediated by specific protein families such as PABPN1 in the nucleus and PABPC1–PABPC4 in the cytoplasm.

Mechanism: The cytoplasmic poly(A)-binding proteins contain RNA recognition motifs that bind poly(A) sequences and, through interactions with translation initiation factors like eIF4G and PABPC, promote mRNA circularization and efficient translation. They also recruit deadenylases or protective complexes to modulate tail length and transcript stability. Nuclear poly(A)-binding protein PABPN1 regulates poly(A) tail length during 3’ end formation and export.

Function and significance: polyAbinding stabilizes mRNA, influences turnover, and coordinates translation with mRNA processing. Binding dynamics depend on tail length, cellular conditions, and protein partners. Abnormal polyAbinding is linked to altered gene expression and disease, reflecting its central role in post-transcriptional regulation.

History and research: The existence of poly(A)-binding proteins was established in the late 20th century; PABPN1 and PABPC family members have been characterized extensively since the 1980s and 1990s. Methods such as RIP, CLIP-Seq, and yeast two-hybrid mapping identify interactions with RNAs and other proteins, helping to map interaction networks and functional consequences.

See also mRNA stability, polyadenylation, translation initiation, deadenylation, PABPN1, PABPC1.