Abstract
Postsynaptic density-95 (PSD-95/SAP-90) is a palmitoylated peripheral membrane protein that scaffolds ion channels at excitatory synapses. To elucidate mechanisms for postsynaptic ion channel clustering, we analyzed the cellular trafficking of PSD-95. We find that PSD-95 transiently associates with a perinuclear membranous compartment and traffics with vesiculotubular structures, which migrate in a microtubule-dependent manner. Trafficking of PSD-95 with these vesiculotubular structures requires dual palmitoylation, which is specified by five consecutive hydrophobic residues at the NH(2) terminus. Mutations that disrupt dual palmitoylation of PSD-95 block both ion channel clustering by PSD-95 and its synaptic targeting. Replacing the palmitoylated NH(2) terminus of PSD-95 with alternative palmitoylation motifs at either the NH(2) or COOH termini restores ion channel clustering also induces postsynaptic targeting, respectively. In brain, we find that PSD-95 occurs not only at PSDs but also in association with intracellular smooth tubular structures in dendrites and spines. These data imply that PSD-95 is an itinerant vesicular protein; initial targeting of PSD-95 to an intracellular membrane compartment may participate in postsynaptic ion channel clustering by PSD-95.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Biological Transport
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Brefeldin A / pharmacology
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Cell Line
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Cell Nucleus / metabolism
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Cell Polarity
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Cerebral Cortex / cytology
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Consensus Sequence
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Disks Large Homolog 4 Protein
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Dogs
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Epithelial Cells / metabolism
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Green Fluorescent Proteins
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Guanylate Kinases
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Humans
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Intracellular Signaling Peptides and Proteins
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Kv1.4 Potassium Channel
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Membrane Proteins
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism*
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Neurons / metabolism
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Nocodazole / pharmacology
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Nucleoside-Phosphate Kinase / metabolism
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Palmitic Acids / metabolism*
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Potassium Channels / metabolism*
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Potassium Channels, Voltage-Gated*
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Rats
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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SAP90-PSD95 Associated Proteins
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Synapses
Substances
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Disks Large Homolog 4 Protein
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Dlg4 protein, rat
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Intracellular Signaling Peptides and Proteins
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KCNA4 protein, human
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Kcna4 protein, rat
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Kv1.4 Potassium Channel
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Luminescent Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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Palmitic Acids
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Potassium Channels
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Potassium Channels, Voltage-Gated
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Recombinant Fusion Proteins
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SAP90-PSD95 Associated Proteins
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postsynaptic density proteins
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Green Fluorescent Proteins
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Brefeldin A
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Nucleoside-Phosphate Kinase
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Guanylate Kinases
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Nocodazole