Abstract
Cytochrome c with a nuclear localization signal added at the N terminus was mistargeted to the nucleus, resulting in a yeast strain deficient in mitochondrial cytochrome c. Reversion of this strain allowed the isolation of temperature-conditional mutants defective in nuclear transport, as demonstrated with one of these mutants, nip1-1, that was shown to be defective in nuclear accumulation of a LacZ protein containing a nuclear localization signal of the yeast ribosomal protein L29. The NIP1+ gene was cloned and shown to encode a 93,143-Da protein. Furthermore, an epitope-labeled NIP1 protein migrated in SDS/polyacrylamide gels with a mass of approximately 100,000 Da and was shown by immunofluorescence to localize mainly in the cytoplasm. NIP1+ was shown to be an essential gene by gene disruption experiments. Intriguingly, NIP1 has a serine-rich acidic N-terminal region that is similar in this regard to the N-terminal region of a previously described nuclear localization signal-binding protein, NSR1.
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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Alleles
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Amino Acid Sequence
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Base Sequence
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Cell Nucleus / metabolism*
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Cloning, Molecular
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Codon / genetics
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Cytochrome c Group / genetics*
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Eukaryotic Initiation Factor-3
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Fungal Proteins / genetics*
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Fungal Proteins / isolation & purification
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Genes, Fungal*
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Genetic Complementation Test
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Immunoblotting
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Nuclear Proteins / genetics*
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Nuclear Proteins / isolation & purification
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Phenotype
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Protein Biosynthesis
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Recombinant Fusion Proteins / isolation & purification
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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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TATA Box
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beta-Galactosidase / genetics
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beta-Galactosidase / isolation & purification
Substances
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Codon
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Cytochrome c Group
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Eukaryotic Initiation Factor-3
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Fungal Proteins
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NIP1 protein, S cerevisiae
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Nuclear Proteins
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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beta-Galactosidase