Evidence for a pioneer round of mRNA translation: mRNAs subject to nonsense-mediated decay in mammalian cells are bound by CBP80 and CBP20.
Nonsense-mediated decay (NMD) eliminates mRNAs that prematurely terminate translation. We used antibody to the nuclear cap binding protein CBP80 or its cytoplasmic counterpart eIF4E to immunopurify RNP containing nonsense-free or nonsense-containing transcripts. Data indicate that NMD takes place in association with CBP80. We defined other components of NMD-susceptible mRNP as CBP20, PABP2, eIF4G, and the NMD factors Upf2 and Upf3. Consistent with the dependence of NMD on translation, the NMD of CBP80-bound mRNA is blocked by cycloheximide or suppressor tRNA. These findings provide evidence that translation can take place in association with CBP80. They also indicate that CBP80-bound mRNA undergoes a "pioneer" round of translation, before CBP80-CBP20 are replaced by eIF4E, and Upf2 and Upf3 proteins dissociate from upstream of exon-exon junctions.
Ishigaki
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Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Avenue, Box 712, Rochester, NY 14642, USA.
Li
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Serin
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Maquat
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D016475:3T3 Cells; D000510:Alpha-Globulins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D018389:Codon, Nonsense / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D039603:Eukaryotic Initiation Factor-4G; D005914:Globins / Q000235:genetics / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D046911:Macromolecular Substances; D051379:Mice; D008954:Models, Biological; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism; D039102:Poly(A)-Binding Proteins; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins; D039381:RNA Cap-Binding Proteins; D012315:RNA Caps / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D000094765:Glutathione Peroxidase GPX1
D000510:Alpha-Globulins; D018389:Codon, Nonsense; D003432:Cross-Linking Reagents; D039603:Eukaryotic Initiation Factor-4G; D046911:Macromolecular Substances; D010448:Peptide Initiation Factors; D039102:Poly(A)-Binding Proteins; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D039381:RNA Cap-Binding Proteins; D012315:RNA Caps; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C035737:major urinary proteins; D005914:Globins; D003513:Cycloheximide; D005979:Glutathione Peroxidase; D000094765:Glutathione Peroxidase GPX1