Abstract
A family of proteins called complexins was discovered that compete with alpha-SNAP, but not synaptotagmin, for SNAP receptor binding. Complexins I and II are highly homologous hydrophilic proteins that are tightly conserved, with 100% identity among mouse, rat, and human complexin II. They are enriched in neurons where they colocalize with syntaxin and SNAP-25; in addition, complexin II is expressed ubiquitously at low levels. Complexins bind weakly to syntaxin alone and not at all to synaptobrevin and SNAP-25, but strongly to the SNAP receptor-core complex composed of these three molecules. They compete with alpha-SNAP for binding to the core complex but not with other interacting molecules, including synaptotagmin I, suggesting that the complexins regulate the sequential interactions of alpha-SNAP and synaptotagmins with the SNAP receptor during exocytosis.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Vesicular Transport
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Amino Acid Sequence
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Animals
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Brain Chemistry
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Calcium / metabolism
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Calcium-Binding Proteins*
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Carrier Proteins / metabolism
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Cytosol / chemistry
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Exocytosis
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Gene Expression
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Hippocampus / cytology
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Humans
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Macromolecular Substances
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Membrane Fusion / physiology*
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Membrane Glycoproteins / metabolism
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Membrane Proteins / metabolism
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Membrane Proteins / physiology*
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Mice
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Molecular Sequence Data
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / isolation & purification
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Nerve Tissue Proteins / metabolism
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Nerve Tissue Proteins / physiology*
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Neurons / chemistry
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R-SNARE Proteins
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Rats
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Recombinant Fusion Proteins / metabolism
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SNARE Proteins
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Sequence Alignment
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Sequence Homology, Amino Acid
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Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
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Species Specificity
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Synaptic Vesicles / metabolism*
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Synaptosomal-Associated Protein 25
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Synaptotagmin I
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Synaptotagmins
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Vesicular Transport Proteins*
Substances
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Adaptor Proteins, Vesicular Transport
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Calcium-Binding Proteins
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Carrier Proteins
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Macromolecular Substances
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Membrane Glycoproteins
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Membrane Proteins
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Nerve Tissue Proteins
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R-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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SYT1 protein, human
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Snap25 protein, mouse
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Snap25 protein, rat
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Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
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Synaptosomal-Associated Protein 25
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Synaptotagmin I
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Syt1 protein, mouse
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Syt1 protein, rat
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Vesicular Transport Proteins
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complexin I
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complexin II
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Synaptotagmins
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Calcium
Associated data
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GENBANK/U35098
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GENBANK/U35099
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GENBANK/U35100
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GENBANK/U35101