A novel tetanus neurotoxin-insensitive vesicle-associated membrane protein in SNARE complexes of the apical plasma membrane of epithelial cells.
The importance of soluble N-ethyl maleimide (NEM)-sensitive fusion protein (NSF) attachment protein (SNAP) receptors (SNAREs) in synaptic vesicle exocytosis is well established because it has been demonstrated that clostridial neurotoxins (NTs) proteolyze the vesicle SNAREs (v-SNAREs) vesicle-associated membrane protein (VAMP)/brevins and their partners, the target SNAREs (t-SNAREs) syntaxin 1 and ... SNAP25. Yet, several exocytotic events, including apical exocytosis in epithelial cells, are insensitive to numerous clostridial NTs, suggesting the presence of SNARE-independent mechanisms of exocytosis. In this study we found that syntaxin 3, SNAP23, and a newly identified VAMP/brevin, tetanus neurotoxin (TeNT)-insensitive VAMP (TI-VAMP), are insensitive to clostridial NTs. In epithelial cells, TI-VAMP-containing vesicles were concentrated in the apical domain, and the protein was detected at the apical plasma membrane by immunogold labeling on ultrathin cryosections. Syntaxin 3 and SNAP23 were codistributed at the apical plasma membrane where they formed NEM-dependent SNARE complexes with TI-VAMP and cellubrevin. We suggest that TI-VAMP, SNAP23, and syntaxin 3 can participate in exocytotic processes at the apical plasma membrane of epithelial cells and, more generally, domain-specific exocytosis in clostridial NT-resistant pathways.
Mesh Terms:
Amino Acid Sequence, Animals, Antigens, Surface, Base Sequence, Botulinum Toxins, Caco-2 Cells, Carrier Proteins, Cell Membrane, DNA, Complementary, Dithiothreitol, Enzyme Inhibitors, Epithelial Cells, Ethylmaleimide, Humans, Membrane Proteins, Metalloendopeptidases, Molecular Sequence Data, Nerve Tissue Proteins, Qa-SNARE Proteins, Qb-SNARE Proteins, Qc-SNARE Proteins, R-SNARE Proteins, Rabbits, Rats, SNARE Proteins, Sequence Homology, Amino Acid, Synaptosomal-Associated Protein 25, Syntaxin 1, Tetanus Toxin, Vesicle-Associated Membrane Protein 3, Vesicular Transport Proteins
Amino Acid Sequence, Animals, Antigens, Surface, Base Sequence, Botulinum Toxins, Caco-2 Cells, Carrier Proteins, Cell Membrane, DNA, Complementary, Dithiothreitol, Enzyme Inhibitors, Epithelial Cells, Ethylmaleimide, Humans, Membrane Proteins, Metalloendopeptidases, Molecular Sequence Data, Nerve Tissue Proteins, Qa-SNARE Proteins, Qb-SNARE Proteins, Qc-SNARE Proteins, R-SNARE Proteins, Rabbits, Rats, SNARE Proteins, Sequence Homology, Amino Acid, Synaptosomal-Associated Protein 25, Syntaxin 1, Tetanus Toxin, Vesicle-Associated Membrane Protein 3, Vesicular Transport Proteins
Mol. Biol. Cell
Date: Jun. 01, 1998
PubMed ID: 9614185
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