Abstract
Syntaxin, synaptosome-associated protein of 25 kD (SNAP25), and vesicle-associated membrane protein/synaptobrevin are collectively called SNAP receptor (SNARE) proteins, and they catalyze neuronal exocytosis by forming a "core complex." The steps in core complex formation are unknown. Here, we monitored SNARE complex formation in vivo with the use of a fluorescent version of SNAP25. In PC12 cells, we found evidence for a syntaxin-SNAP25 complex that formed with high affinity, required only the amino-terminal SNARE motif of SNAP25, tolerated a mutation that blocks formation of other syntaxin-SNAP25 complexes, and assembled reversibly when Ca2+ entered cells during depolarization. The complex may represent a precursor to the core complex formed during a Ca2+-dependent priming step of exocytosis.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adrenal Medulla / cytology
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Animals
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Bacterial Proteins
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Cell Line
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Fluorescence Resonance Energy Transfer
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Green Fluorescent Proteins
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Humans
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Luminescent Proteins
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Membrane Proteins / genetics
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Membrane Proteins / physiology
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / physiology
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PC12 Cells
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Qa-SNARE Proteins
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Rats
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Recombinant Fusion Proteins
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SNARE Proteins
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Synaptosomal-Associated Protein 25
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Vesicular Transport Proteins / physiology*
Substances
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Bacterial Proteins
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Cyan Fluorescent Protein
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Luminescent Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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Qa-SNARE Proteins
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Recombinant Fusion Proteins
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SNAP25 protein, human
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SNARE Proteins
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Snap25 protein, rat
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Synaptosomal-Associated Protein 25
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Vesicular Transport Proteins
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yellow fluorescent protein, Bacteria
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Green Fluorescent Proteins