Abstract
We report the purification of a presynaptic "particle web" consisting of approximately 50 nm pyramidally shaped particles interconnected by approximately 100 nm spaced fibrils. This is the "presynaptic grid" described in early EM studies. It is completely soluble above pH 8, but reconstitutes after dialysis against pH 6. Interestingly, reconstituted particles orient and bind PSDs asymmetrically. Mass spectrometry of purified web components reveals major proteins involved in the exocytosis of synaptic vesicles and in membrane retrieval. Our data support the idea that the CNS synaptic junction is organized by transmembrane adhesion molecules interlinked in the synaptic cleft, connected via their intracytoplasmic domains to the presynaptic web on one side and to the postsynaptic density on the other. The CNS synaptic junction may therefore be conceptualized as a complicated macromolecular scaffold that isostatically bridges two closely aligned plasma membranes.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Antibodies
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Cadherins / analysis
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Cadherins / immunology
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Cell Membrane / chemistry
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Cell Membrane / metabolism
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Cell Membrane / ultrastructure
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Clathrin / analysis
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Clathrin / immunology
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Clathrin Heavy Chains
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Dynamins
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GTP Phosphohydrolases / analysis
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GTP Phosphohydrolases / immunology
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HSP70 Heat-Shock Proteins / analysis
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HSP70 Heat-Shock Proteins / immunology
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Male
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Membrane Proteins / analysis
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Membrane Proteins / immunology
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Microscopy, Immunoelectron
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Munc18 Proteins
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Myosin Heavy Chains / analysis
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Myosin Heavy Chains / immunology
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Nerve Tissue Proteins / analysis
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Nerve Tissue Proteins / immunology
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Neurofilament Proteins / analysis
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Neurofilament Proteins / immunology
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Presynaptic Terminals / chemistry*
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Presynaptic Terminals / metabolism
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Presynaptic Terminals / ultrastructure*
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Qa-SNARE Proteins
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Rabbits
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Rats
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Spectrin / analysis
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Spectrin / immunology
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Synapsins / analysis
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Synapsins / immunology
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Synaptic Vesicles / chemistry*
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Synaptic Vesicles / metabolism
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Synaptic Vesicles / ultrastructure*
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Synaptosomal-Associated Protein 25
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Vesicular Transport Proteins*
Substances
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Antibodies
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Cadherins
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Clathrin
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HSP70 Heat-Shock Proteins
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Membrane Proteins
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Munc18 Proteins
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Nerve Tissue Proteins
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Neurofilament Proteins
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Qa-SNARE Proteins
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Snap25 protein, rat
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Synapsins
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Synaptosomal-Associated Protein 25
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Vesicular Transport Proteins
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Clathrin Heavy Chains
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Spectrin
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GTP Phosphohydrolases
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Myosin Heavy Chains
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Dynamins