Abstract
The intracellular localization of the S. cerevisiae transcription factor SWI5 is cell cycle dependent. The protein is nuclear in G1 cells but cytoplasmic in S, G2, and M phase cells. We have identified SWI5's nuclear localization signal (NLS) and show that it can confer cell cycle-dependent nuclear entry to a heterologous protein. Located within or close to the NLS are three serine residues, mutation of which results in constitutive nuclear entry. These residues are phosphorylated in a cell cycle-dependent manner in vivo, being phosphorylated when SWI5 is in the cytoplasm and dephosphorylated when it is in the nucleus. As all three serines are phosphorylated by purified CDC28-dependent H1 kinase activity in vitro, we propose a model in which the CDC28 kinase acts directly to control nuclear entry of SWI5.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Cell Compartmentation
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Cell Cycle Proteins*
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Cell Cycle*
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Cell Nucleus / metabolism*
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Cloning, Molecular
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DNA Mutational Analysis
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DNA-Binding Proteins*
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Fungal Proteins / chemistry
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Fungal Proteins / metabolism*
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Gene Expression Regulation, Fungal
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Histones / metabolism
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Maturation-Promoting Factor / metabolism*
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Molecular Sequence Data
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Peptide Mapping
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Phosphoproteins / metabolism
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Phosphorylation
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Protamine Kinase / metabolism*
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Protein Kinases / physiology*
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae Proteins*
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Transcription Factors / chemistry
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Transcription Factors / metabolism*
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Transcription, Genetic
Substances
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Cell Cycle Proteins
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DNA-Binding Proteins
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Fungal Proteins
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Histones
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Phosphoproteins
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SWI5 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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Protein Kinases
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Protamine Kinase
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Maturation-Promoting Factor