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Subcellular Localisation of 14-3-3 Isoforms in Rat Brain Using Specific Antibodies

Authors

  • H. Martin,

    1. Laboratory of Protein Structure, National Institute for Medical Research, London, England; and
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    • The current address of Dr. H. Martin is Proteus Molecular Design Ltd., Proteus House, Lyme Green Business Park, Macclesfield, Cheshire SK11 OJL, U.K.

  • J. Rostas,

    1. Neuroscience Group, Faculty of Medicine, University of Newcastle, Newcastle, New South Wales, Australia
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  • Y. Patel,

    1. Laboratory of Protein Structure, National Institute for Medical Research, London, England; and
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  • A. Aitken

    Corresponding author
    1. Laboratory of Protein Structure, National Institute for Medical Research, London, England; and
      Address correspondence and reprint requests to Dr. A. Aitken at Laboratory of Protein Structure, National Institute for Medical Research, Mill Hill, London NW7 1AA, U.K.
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Address correspondence and reprint requests to Dr. A. Aitken at Laboratory of Protein Structure, National Institute for Medical Research, Mill Hill, London NW7 1AA, U.K.

Abstract

Abstract: The 14-3-3 protein family, which is present at particularly high concentrations in mammalian brain, is known to be involved in various cellular functions, including protein kinase C regulation and exocytosis. Despite the fact that most of the 14-3-3 proteins are cytosolic, a small but significant proportion of 14-3-3 in brain is tightly and selectively associated with some membranes. Using a panel of isoform-specific antisera we find that the ε, η, γ, β, and ζ isoforms are all present in purified synaptic membranes but absent from mitochondrial and myelin membranes. In addition, the η, ε, and γ isoforms but not the β and ζ isoforms are associated with isolated synaptic junctions. When different populations of synaptosomes were fractionated by a nonequilibrium Percoll gradient procedure, the ε and γ isoforms were present and the β and ζ isoforms were absent from the membranes of synaptosomes sedimenting in the more dense parts of the gradient. The finding that these proteins are associated with different populations of synaptic membranes suggests that they are selectively expressed in different classes of neurones and raises the possibility that some or all of them may influence neurotransmission by regulating exocytosis and/or phosphorylation.

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