Abstract
1. In cells of epithelial origin the protein tyrosine phosphatase PTP-BL is predominantly localized at the apical membrane of polarized cells. This large submembranous multidomain PTP is also expressed in cells of neuronal origin. We studied the localization of PTP-BL in mouse neuroblastoma cells utilizing EGFP-tagged versions of the protein. 2. In proliferating Neuro-2a cells, immunofluorescence and immuno-electron microscopy revealed a submembranous FERM domain-dependent localization at cell-cell boundaries for EGFP-PTP-BL. Additionally, significant amounts of EGFP-PTP-BL are located in the cytoplasm as well as in nuclei. Upon serum depletion-induced differentiation of Neuro-2a cells, a partial shift of EGFP-PTP-BL from a cortical localization to cytoskeleton-like F-actin-positive structures is observed. Parallel biochemical studies corroborate this finding and reveal a serum depletion-induced shift of EFGP-PTP-BL from a membrane(-associated) fraction to an NP40-soluble cytoskeletal fraction. 3. Different pools of PTP-BL-containing protein complexes can be discerned in neuronal cells, reflecting distinct molecular microenvironments in which PTP-BL may exert its function.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actin Cytoskeleton / enzymology
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Actin Cytoskeleton / ultrastructure
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Actins / metabolism
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Animals
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Cell Compartmentation / drug effects
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Cell Compartmentation / physiology
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Cell Differentiation / drug effects
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Cell Differentiation / physiology*
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Cell Line, Tumor
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Cell Membrane / enzymology*
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Cell Membrane / ultrastructure
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Cell Nucleus / enzymology
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Cell Nucleus / ultrastructure
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Cells, Cultured
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Culture Media, Serum-Free / pharmacology
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Cytoplasm / enzymology
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Cytoplasm / ultrastructure
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Cytoskeleton / enzymology*
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Cytoskeleton / ultrastructure
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Green Fluorescent Proteins
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Macromolecular Substances / metabolism
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Mice
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Neuroblastoma
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Neurons / enzymology*
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Neurons / ultrastructure
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Protein Structure, Tertiary / physiology
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Protein Transport / drug effects
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Protein Transport / physiology
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Protein Tyrosine Phosphatase, Non-Receptor Type 13
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Protein Tyrosine Phosphatases / chemistry
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Protein Tyrosine Phosphatases / metabolism*
Substances
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Actins
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Culture Media, Serum-Free
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Macromolecular Substances
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enhanced green fluorescent protein
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Green Fluorescent Proteins
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Protein Tyrosine Phosphatase, Non-Receptor Type 13
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Protein Tyrosine Phosphatases
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Ptpn13 protein, mouse