Abstract
From transcription to translation, mRNA is complexed with heterogeneous nuclear ribonucleoproteins (hnRNP proteins) that mediate mRNA processing, export from the nucleus, and delivery into the cytoplasm. Although the mechanism is unknown, export of mature mRNA from the nucleus is a critical regulatory step in gene expression. Analyses of hnRNP proteins have shown that many of these proteins are required for this essential cellular process. In this study, we characterize the Saccharomyces cerevisiae Nab2 protein, which was first identified as a poly(A) RNA-binding protein (Anderson, J. T., Wilson, S. M., Datar, K. V., and Swanson, M. S. (1993) Mol. Cell. Biol. 13, 2730-2741). Our work indicates that poly(A) RNA export from the nucleus is dependent upon a functional Nab2 protein; correspondingly, export of Nab2p from the nucleus is dependent upon ongoing RNA polymerase II transcription. Furthermore, we show that Nab2p is modified within its RGG domain by the type I protein-arginine methyltransferase, Hmt1p. Our experiments demonstrate that arginine methylation is required for the export of Nab2p from the nucleus and therefore establish an in vivo effect of this modification. Overall, these experiments provide evidence that Nab2p is an hnRNP protein that is required for poly(A) RNA export and whose export from the nucleus is regulated by Hmt1p.
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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ATP-Binding Cassette Transporters / metabolism*
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Amino Acid Sequence
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Arginine / chemistry
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Arginine / metabolism*
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Cell Nucleus / metabolism
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Escherichia coli / metabolism
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Fluorescent Antibody Technique, Indirect
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Fungal Proteins / metabolism*
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Fungal Proteins / physiology*
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Gene Deletion
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Green Fluorescent Proteins
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Immunoblotting
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In Situ Hybridization, Fluorescence
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Luminescent Proteins / metabolism
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Methylation
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Molecular Sequence Data
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Nucleocytoplasmic Transport Proteins*
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Plasmids / metabolism
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Poly A / metabolism*
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Precipitin Tests
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Protein Binding
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Protein Biosynthesis
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Protein Transport
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Protein-Arginine N-Methyltransferases*
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RNA / metabolism*
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RNA Polymerase II / metabolism
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RNA, Messenger / metabolism
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RNA-Binding Proteins / metabolism*
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RNA-Binding Proteins / physiology*
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Recombinant Fusion Proteins / metabolism
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Repressor Proteins*
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Temperature
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Transcription, Genetic
Substances
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ATP-Binding Cassette Transporters
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Fungal Proteins
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Luminescent Proteins
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NAB2 protein, S cerevisiae
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Nucleocytoplasmic Transport Proteins
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RNA, Messenger
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RNA-Binding Proteins
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Recombinant Fusion Proteins
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Repressor Proteins
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Saccharomyces cerevisiae Proteins
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Green Fluorescent Proteins
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Poly A
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RNA
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Arginine
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HMT1 protein, S cerevisiae
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Protein-Arginine N-Methyltransferases
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RNA Polymerase II