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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.

Pubmed ID: 9614185


  • Galli T
  • Zahraoui A
  • Vaidyanathan VV
  • Raposo G
  • Tian JM
  • Karin M
  • Niemann H
  • Louvard D


Molecular biology of the cell

Publication Data

June 10, 1998

Associated Grants


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