Abstract
The nuclear pore complex mediates macromolecular transport between the nucleus and cytoplasm. Many nuclear pore components (nucleoporins) are modified by both phosphate and O-linked N-acetylglucosamine (O-GlcNAc). Among its many functions, protein phosphorylation plays essential roles in cell cycle progression. The role of O-GlcNAc addition is unknown. Here, levels of nucleoporin phosphorylation and glycosylation during cell cycle progression are examined. Whereas nuclear pore glycoproteins are phosphorylated in a cell-cycle-dependent manner, levels of O-GlcNAc remain constant. The major nucleoporin p62 can be phosphorylated in vitro by protein kinase A and glycogen synthase kinase (GSK)-3alpha but not by cyclin B/cdc2 or GSK-3beta. The consensus sites of these kinases resemble sites which can be glycosylated by O-GlcNAc transferase. These data are consistent with a model that O-GlcNAc limits nucleoporin hyperphosphorylation during M-phase and hastens the resumption of regulated nuclear transport at the completion of cell division.
Copyright 1999 Academic Press.
MeSH terms
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Acetylglucosamine / metabolism*
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Amino Acid Sequence
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Animals
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CDC2 Protein Kinase / metabolism
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism
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Cell Cycle
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Cell Line
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Galactose / metabolism
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Glycogen Synthase Kinase 3
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Glycogen Synthase Kinases
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Glycoproteins / metabolism
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Glycosylation
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Membrane Glycoproteins / immunology
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Membrane Glycoproteins / metabolism*
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Molecular Sequence Data
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Nuclear Envelope / metabolism*
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Nuclear Pore Complex Proteins
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Nuclear Proteins / immunology
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Nuclear Proteins / metabolism*
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Oocytes
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Phosphates / metabolism*
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Phosphorylation
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Precipitin Tests
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Protein Binding
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Protein Isoforms / metabolism
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Rats
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Wheat Germ Agglutinins / metabolism
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Xenopus laevis
Substances
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Glycoproteins
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Membrane Glycoproteins
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Nuclear Pore Complex Proteins
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Nuclear Proteins
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Phosphates
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Protein Isoforms
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Wheat Germ Agglutinins
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nuclear pore protein p62
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Glycogen Synthase Kinases
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Cyclic AMP-Dependent Protein Kinases
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Calcium-Calmodulin-Dependent Protein Kinases
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CDC2 Protein Kinase
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Glycogen Synthase Kinase 3
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Acetylglucosamine
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Galactose