Abstract
Ca2+-regulated exocytosis of lysosomes has been recognized recently as a ubiquitous process, important for the repair of plasma membrane wounds. Lysosomal exocytosis is regulated by synaptotagmin VII, a member of the synaptotagmin family of Ca2+-binding proteins localized on lysosomes. Here we show that Ca2+-dependent interaction of the synaptotagmin VII C(2)A domain with SNAP-23 is facilitated by syntaxin 4. Specific interactions also occurred in cell lysates between the plasma membrane t-SNAREs SNAP-23 and syntaxin 4 and the lysosomal v-SNARE TI-VAMP/VAMP7. Following cytosolic Ca2+ elevation, SDS-resistant complexes containing SNAP-23, syntaxin 4, and TI-VAMP/VAMP7 were detected on membrane fractions. Lysosomal exocytosis was inhibited by the SNARE domains of syntaxin 4 and TI-VAMP/VAMP7 and by cleavage of SNAP-23 with botulinum neurotoxin E, thereby functionally implicating these SNAREs in Ca2+-regulated exocytosis of conventional lysosomes.
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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Antigens, CD / metabolism
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Bacterial Proteins
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Calcium / 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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Cell Membrane / metabolism
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Cell Survival
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DNA / chemistry
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Dose-Response Relationship, Drug
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Electroporation
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Exocytosis*
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Flow Cytometry
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Lysosomal Membrane Proteins
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Lysosomes / metabolism*
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Membrane Glycoproteins / metabolism
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Membrane Glycoproteins / physiology*
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Membrane Proteins / metabolism*
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Microscopy, Fluorescence
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Nerve Tissue Proteins / metabolism
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Nerve Tissue Proteins / physiology*
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Precipitin Tests
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Protein Binding
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Protein Isoforms
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Protein Structure, Tertiary
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Qa-SNARE Proteins
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Qb-SNARE Proteins
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Qc-SNARE Proteins
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R-SNARE Proteins
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Rats
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Recombinant Proteins / chemistry
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SNARE Proteins
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Streptolysins / pharmacology
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Synaptotagmins
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Vesicular Transport Proteins*
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beta-N-Acetylhexosaminidases / chemistry
Substances
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Antigens, CD
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Bacterial Proteins
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Calcium-Binding Proteins
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Carrier Proteins
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Lysosomal Membrane Proteins
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Membrane Glycoproteins
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Membrane Proteins
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Nerve Tissue Proteins
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Protein Isoforms
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Qa-SNARE Proteins
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Qb-SNARE Proteins
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Qc-SNARE Proteins
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R-SNARE Proteins
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Recombinant Proteins
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SNAP23 protein, human
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SNARE Proteins
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Streptolysins
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Syt7 protein, rat
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Vamp7 protein, rat
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Vesicular Transport Proteins
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streptolysin O
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Synaptotagmins
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DNA
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beta-N-Acetylhexosaminidases
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Calcium