Abstract
A mutation in the Saccharomyces cerevisiae SEN1 gene causes accumulation of end-matured, intron-containing pre-tRNAs. Cells containing the thermosensitive sen1-1 mutation exhibit reduced tRNA splicing endonuclease activity. However, Sen1p is not the catalytic subunit of this enzyme. We have used Sen1p-specific antibodies for cell fractionation studies and immunofluorescent microscopy and determined that Sen1p is a low abundance protein of about 239 kDa. It localizes to the nucleus with a granular distribution. We verified that a region in SEN1 containing a putative nuclear localization signal sequence (NLS) is necessary for nuclear targeting. Furthermore, we found that inactivation of Sen1p by temperature shift of a strain carrying sen1-1 leads to mislocalization of two nucleolar proteins, Nop1 and Ssb1. Possible mechanisms are discussed for several related nuclear functions of Sen1p, including tRNA splicing and the maintenance of a normal crescent-shaped nucleolus.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Biological Transport
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Cell Compartmentation*
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Cell Nucleolus / metabolism*
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Cell Nucleus / metabolism
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DNA Helicases
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Fluorescent Antibody Technique, Indirect
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Genes, Fungal
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HSP70 Heat-Shock Proteins
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Molecular Sequence Data
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Mutation
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Nuclear Proteins / metabolism
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RNA Helicases
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RNA Ligase (ATP) / deficiency
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RNA Precursors / metabolism
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RNA Splicing
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RNA, Transfer / metabolism
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Ribonucleoproteins, Small Nucleolar*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Sequence Deletion
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Structure-Activity Relationship
Substances
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Fungal Proteins
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HSP70 Heat-Shock Proteins
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NOP1 protein, S cerevisiae
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Nuclear Proteins
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RNA Precursors
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Ribonucleoproteins, Small Nucleolar
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SSB1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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RNA, Transfer
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SEN1 protein, S cerevisiae
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DNA Helicases
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RNA Helicases
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RNA Ligase (ATP)