Abstract
While performing a yeast two-hybrid library screen to uncover novel PP2A-interacting proteins, we discovered a specific interaction between a member of the importin beta/karyopherin beta superfamily, importin 9, and the A subunit of PP2A (PR65). This interaction between importin 9 and the A subunit was confirmed by in vitro pulldown, immunoprecipitation, and microcystin-Sepharose chromatography. We also found that another family member, importin beta, interacted specifically with the A subunit of PP2A. Finally, we showed that treatment of cells with a concentration of okadaic acid known to inhibit PP2A impeded the nuclear localization of an NLS-containing protein. These results provide evidence that these importins can exist in a native complex with endogenous PP2A and that this serine/threonine phosphatase plays a role in regulating the nuclear import of NLS-containing proteins in vivo.
MeSH terms
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Active Transport, Cell Nucleus / drug effects
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Animals
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Binding Sites
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Enzyme Inhibitors / pharmacology
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HeLa Cells
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Humans
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Mice
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Nuclear Localization Signals / chemistry
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Nuclear Localization Signals / genetics
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Nuclear Localization Signals / metabolism
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Okadaic Acid / pharmacology
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Phosphoprotein Phosphatases / antagonists & inhibitors
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Phosphoprotein Phosphatases / chemistry
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Phosphoprotein Phosphatases / genetics
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Phosphoprotein Phosphatases / metabolism*
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Protein Phosphatase 2
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Protein Subunits
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Two-Hybrid System Techniques
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beta Karyopherins / chemistry
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beta Karyopherins / genetics
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beta Karyopherins / metabolism*
Substances
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Enzyme Inhibitors
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Nuclear Localization Signals
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PPP2R1B protein, human
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Ppp2r1b protein, mouse
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Protein Subunits
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Recombinant Fusion Proteins
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beta Karyopherins
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importin 9, mouse
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Okadaic Acid
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Phosphoprotein Phosphatases
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Protein Phosphatase 2