| Modification Notes |
Various PABP-interacting proteins bind to and regulate the activity of polyadenylate-binding protein (PABP), an essential, well-conserved, multifunctional protein involved in translational initiation, mRNA biogenesis and degradation. PABP enhances translation by circularizing mRNA through its interaction with the translation initiation factor eIF4G and mRNA's poly(A) tail. PABP-interacting proteins include PaiP1, a translational stimulator, and Paip2a and Paip2b, translational inhibitors. Paip1 is thought to act as a translational activator in 5' cap-dependent translation by interacting with PABP and the initiation factors eIF4A and eIF3, whereas Paip2 decreases the affinity of PABP for polyadenylate RNA, and disrupts the repeating structure of poly(A) ribonucleoprotein. Paip2b (poly(A) binding protein interacting protein 2B) is a 123 amino acid protein that may be involved in regulating PABP activity. |