Abstract
Syntaxins and Sec1/munc18 proteins are central to intracellular membrane fusion. All syntaxins comprise a variable N-terminal region, a conserved SNARE motif that is critical for SNARE complex formation, and a transmembrane region. The N-terminal region of neuronal syntaxin 1A contains a three-helix domain that folds back onto the SNARE motif forming a 'closed' conformation; this conformation is required for munc18-1 binding. We have examined the generality of the structural properties of syntaxins by NMR analysis of Vam3p, a yeast syntaxin essential for vacuolar fusion. Surprisingly, Vam3p also has an N-terminal three-helical domain despite lacking apparent sequence homology with syntaxin 1A in this region. However, Vam3p does not form a closed conformation and its N-terminal domain is not required for binding to the Sec1/munc18 protein Vps33p, suggesting that critical distinctions exist in the mechanisms used by syntaxins to govern different types of membrane fusion.
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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Amino Acid Sequence
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Antigens, Surface / chemistry
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Antigens, Surface / metabolism
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Carrier Proteins*
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Conserved Sequence*
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Fungal Proteins / chemistry*
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Membrane Fusion
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Membrane Proteins / chemistry*
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Membrane Proteins / metabolism*
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Models, Molecular
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Molecular Sequence Data
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Mutation
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / metabolism
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Nuclear Magnetic Resonance, Biomolecular
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Peptide Fragments / chemistry
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Peptide Fragments / metabolism
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Protein Binding
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Protein Structure, Tertiary
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Qa-SNARE Proteins
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Saccharomyces cerevisiae / chemistry
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Saccharomyces cerevisiae Proteins*
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Sequence Alignment
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Structure-Activity Relationship
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Syntaxin 1
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Vesicular Transport Proteins*
Substances
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Antigens, Surface
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Carrier Proteins
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Fungal Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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Peptide Fragments
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Qa-SNARE Proteins
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SSO1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Syntaxin 1
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VAM3 protein, S cerevisiae
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VPS33 protein, S cerevisiae
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Vesicular Transport Proteins