title: eIF4AIII binds spliced mRNA in the exon junction complex and is essential for nonsense-mediated decay.
abstract: The exon junction complex (EJC), a set of proteins deposited on mRNAs as a consequence of pre-mRNA splicing, is a key effector of downstream mRNA metabolism. We have identified eIF4AIII, a member of the eukaryotic translation initiation factor 4A family of RNA helicases (also known as DExH/D box proteins), as a novel EJC core component. Crosslinking and antibody inhibition studies suggest that eIF4AIII constitutes at least part of the platform anchoring other EJC components to spliced mRNAs. A nucleocytoplasmic shuttling protein, eIF4AIII associates in vitro and in vivo with two other EJC core factors, Y14 and Magoh. In mammalian cells, eIF4AIII is essential for nonsense-mediated mRNA decay (NMD). Finally, a model is proposed by which eIF4AIII represents a new functional class of DExH/D box proteins that act as RNA clamps or 'place holders' for the sequence-independent attachment of additional factors to RNAs.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, USA.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Shibuya
authors.forename: Thomas Ø
authors.initials: TØ
authors.lastname: Tange
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Moore
mesh_terms: D001665:Binding Sites; D018389:Codon, Nonsense; D039601:Eukaryotic Initiation Factor-4A / Q000378:metabolism*; D005091:Exons / Q000235:genetics*; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007700:Kinetics; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D018389:Codon, Nonsense; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; D039601:Eukaryotic Initiation Factor-4A