title: A novel role of the mammalian GSPT/eRF3 associating with poly(A)-binding protein in Cap/Poly(A)-dependent translation.
abstract: The mammalian GSPT, which consists of amino-terminal (N) and carboxyl-terminal (C) domains, functions as the eukaryotic releasing factor 3 (eRF3) by interacting with eRF1 in translation termination. This function requires only the C-domain that is homologous to the elongation factor (EF) 1alpha, while the N-domain interacts with polyadenylate-binding protein (PABP), which binds the poly(A) tail of mRNA and associates with the eukaryotic initiation factor (eIF) 4G. Here we describe a novel role of GSPT in translation. We first determined an amino acid sequence required for the PABP interaction in the N-domain. Inhibition of this interaction significantly attenuated translation of capped/poly(A)-tailed mRNA not only in an in vitro translation system but also in living cells. There was a PABP-dependent linkage between the termination factor complex eRF1-GSPT and the initiation factor eIF4G associating with 5' cap through eIF4E. Although the inhibition of the GSPT-PABP interaction did not affect the de novo formation of an 80 S ribosomal initiation complex, it appears to suppress the subsequent recycle of ribosome. These results indicate that GSPT/eRF3 plays an important role in translation cycle through the interaction with PABP, in addition to mediating the termination with eRF1.
authors.affiliation: Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Uchida
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Hoshino
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Imataka
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Katada
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D016296:Mutagenesis; D010454:Peptide Termination Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D014176:Protein Biosynthesis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D014162:Transfection
chemical_list: D010454:Peptide Termination Factors; D039102:Poly(A)-Binding Proteins; D011993:Recombinant Fusion Proteins; C087971:peptide-chain-release factor 3; D005982:Glutathione Transferase