Poly(A)-binding protein

Poly(A) RNA binding protein PABP (PDB 1CVJ)

Poly(A)-binding protein (PAB or PABP)[1] is an RNA-binding protein which triggers the binding of eukaryotic initiation factor 4 complex (eIF4G) directly to the poly(A) tail of mRNA which is 200-250 nucleotides long.[2] The poly(A) tail is located on the 3' end of mRNA and was discovered by Mary Edmonds,[3] who also characterized the poly-A polymerase enzyme that generates the poly(a) tail.[4] The binding protein is also involved in mRNA precursors by helping polyadenylate polymerase add the poly(A) nucleotide tail to the pre-mRNA before translation.[5] The nuclear isoform selectively binds to around 50 nucleotides and stimulates the activity of polyadenylate polymerase by increasing its affinity towards RNA. Poly(A)-binding protein is also present during stages of mRNA metabolism including nonsense-mediated decay and nucleocytoplasmic trafficking. The poly(A)-binding protein may also protect the tail from degradation and regulate mRNA production. Without these two proteins in-tandem, then the poly(A) tail would not be added and the RNA would degrade quickly.[6]

  1. ^ Kahvejian A, Svitkin YV, Sukarieh R, M'Boutchou MN, Sonenberg N (January 2005). "Mammalian poly(A)-binding protein is a eukaryotic translation initiation factor, which acts via multiple mechanisms". Genes & Development. 19 (1): 104–13. doi:10.1101/gad.1262905. PMC 540229. PMID 15630022.
  2. ^ Poly(A)-Binding+Proteins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
  3. ^ Edmonds M, Vaughan MH, Nakazato H (June 1971). "Polyadenylic acid sequences in the heterogeneous nuclear RNA and rapidly-labeled polyribosomal RNA of HeLa cells: possible evidence for a precursor relationship". Proceedings of the National Academy of Sciences of the United States of America. 68 (6): 1336–40. doi:10.1073/pnas.68.6.1336. PMC 389184. PMID 5288383.
  4. ^ Winters MA, Edmonds M (July 1973). "A poly(A) polymerase from calf thymus. Purification and properities of the enzyme". The Journal of Biological Chemistry. 248 (13): 4756–62. doi:10.1016/s0021-9258(19)43729-0. PMID 4718742.
  5. ^ "UniProtKB - Q86U42 (PABP2_HUMAN)". uniprot.org. Retrieved 17 November 2015.
  6. ^ Voet D, Voet J. Biochemistry (4th ed.). Wiley. p. 1304.