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EMBO J. 1998 Jun 15;17(12):3484-94.

Binary specification of nonsense codons by splicing and cytoplasmic translation.

Author information

1
Department of Pediatrics, Charité-Virchow Medical Center, Humboldt University, Berlin, Germany.

Abstract

Premature translation termination codons resulting from nonsense or frameshift mutations are common causes of genetic disorders. Complications arising from the synthesis of C-terminally truncated polypeptides can be avoided by 'nonsense-mediated decay' of the mutant mRNAs. Premature termination codons in the beta-globin mRNA cause the common recessive form of beta-thalassemia when the affected mRNA is degraded, but the more severe dominant form when the mRNA escapes nonsense-mediated decay. We demonstrate that cells distinguish a premature termination codon within the beta-globin mRNA from the physiological translation termination codon by a two-step specification mechanism. According to the binary specification model proposed here, the positions of splice junctions are first tagged during splicing in the nucleus, defining a stop codon operationally as a premature termination codon by the presence of a 3' splicing tag. In the second step, cytoplasmic translation is required to validate the 3' splicing tag for decay of the mRNA. This model explains nonsense-mediated decay on the basis of conventional molecular mechanisms and allows us to propose a common principle for nonsense-mediated decay from yeast to man.

PMID:
9628884
PMCID:
PMC1170685
DOI:
10.1093/emboj/17.12.3484
[Indexed for MEDLINE]
Free PMC Article
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