Bühler M Wilkinson MF Mühlemann O 2002 Most vertebrate mRNAs with premature termination codons (PTCs) are specifically recognized and degraded by a process referred to as nonsense-mediated mRNA decay (NMD) while still associated with the nucleus. However, it is still a matter of debate whether PTCs can be identified by intranuclear scanning or only by ribosomes on the cytoplasmic side of the nuclear envelope. Here we show that inhibition of mRNA export by two independent approaches does not affect the downregulation of PTC-containing T-cell receptor beta transcripts in the nuclear fraction of mammalian cells, providing strong evidence for intranuclear NMD. Our results are fully consistent with recently reported evidence for nuclear translation and suggest that an important biological role for nuclear ribosomes is the early elimination of nonsense mRNA during a pioneer round of translation. application/pdf https://sonar.ch/global/documents/284384 eng info:eu-repo/semantics/altIdentifier/doi/10.1093/embo-reports/kvf129 info:eu-repo/semantics/altIdentifier/pmid/12101097 info:eu-repo/semantics/openAccess EMBO reports. - 2002 Active Transport, Cell Nucleus Animals Cell Fractionation Cell Nucleus Codon, Nonsense Green Fluorescent Proteins HeLa Cells Humans In Situ Hybridization, Fluorescence Luminescent Proteins Oocytes Protein Biosynthesis RNA, Messenger Recombinant Fusion Proteins Ribosomes Viral Matrix Proteins Xenopus laevis Intranuclear degradation of nonsense codon-containing mRNA. http://purl.org/coar/resource_type/c_6501