The vesicle-associated membrane protein family of proteins in rat pancreatic and parotid acinar cells.
OBJECTIVE
The vesicle-associated membrane protein (VAMP) family of proteins may play an important role in regulating enzyme secretion from pancreatic and parotid acini. The purpose of this study was to characterize the isoforms produced in pancreatic and parotid acini and determine their subcellular locations.


METHODS
Using a battery of specific antisera and recombinant tetanus toxin light chain (which cleaves VAMP-2 and cellubrevin), the presence of each VAMP molecule in the acini was determined by immunoblotting of subcellular membrane fractions; their localization was determined by confocal immunofluorescence microscopy and immunogold electron microscopy.


RESULTS
Both VAMP-2 and cellubrevin were present on both the zymogen granule membrane and plasma membrane. VAMP-1 was not present in the acinar cell but was found in the nerve endings innervating the acini. As expected, pancreatic acinar VAMP-2 and cellubrevin were sensitive to cleavage by recombinant tetanus toxin.


CONCLUSIONS
VAMP-2 and cellubrevin may play integral roles in exocytosis of the pancreatic and parotid acinar cells, whereas VAMP-1 is restricted to nerves that innervate the acini and may function to modulate exocrine activity.
Gaisano
H Y
HY
Department of Medicine, University of Toronto, Ontario, Canada.
Sheu
L
L
Grondin
G
G
Ghai
M
M
Bouquillon
A
A
Lowe
A
A
Beaudoin
A
A
Trimble
W S
WS
D000818:Animals; D019084:Fluorescent Antibody Technique, Indirect; D015151:Immunoblotting; D008297:Male; D008565:Membrane Proteins / Q000032:analysis*; D018613:Microscopy, Confocal; D010179:Pancreas / Q000378:metabolism*; D010306:Parotid Gland / Q000378:metabolism*; D050683:R-SNARE Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley
D008565:Membrane Proteins; D050683:R-SNARE Proteins