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Mol Cell Biol. 2004 Nov;24(21):9646-57.

Nuclear pre-mRNA decapping and 5' degradation in yeast require the Lsm2-8p complex.

Author information

  • 1Wellcome Trust Centre for Cell Biology, King's Buildings, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.

Abstract

Previous analyses have identified related cytoplasmic Lsm1-7p and nuclear Lsm2-8p complexes. Here we report that mature heat shock and MET mRNAs that are trapped in the nucleus due to a block in mRNA export were strongly stabilized in strains lacking Lsm6p or the nucleus-specific Lsm8p protein but not by the absence of the cytoplasmic Lsm1p. These nucleus-restricted mRNAs remain polyadenylated until their degradation, indicating that nuclear mRNA degradation does not involve the incremental deadenylation that is a key feature of cytoplasmic turnover. Lsm8p can be UV cross-linked to nuclear poly(A)(+) RNA, indicating that an Lsm2-8p complex interacts directly with nucleus-restricted mRNA. Analysis of pre-mRNAs that contain intronic snoRNAs indicates that their 5' degradation is specifically inhibited in strains lacking any of the Lsm2-8p proteins but Lsm1p. Nucleus-restricted mRNAs and pre-mRNA degradation intermediates that accumulate in lsm mutants remain 5' capped. We conclude that the Lsm2-8p complex normally targets nuclear RNA substrates for decapping.

PMID:
15485930
[PubMed - indexed for MEDLINE]
PMCID:
PMC522261
Free PMC Article

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