VESICLE-ASSOCIATED MEMBRANE-PROTEIN (VAMP) SYNAPTOBREVIN-2 IS ASSOCIATED WITH DENSE CORE SECRETORY GRANULES IN PC12 NEUROENDOCRINE CELLS

The presence and intracellular distribution of vesicle-associated memb rane protein-1 (VAMP-1) and VAMP-2 were investigated in the PC12 neuro endocrine cell line using isotype-specific polyclonal antibodies. VAMP -2 was detected in the total membrane fraction, while VAMP-1 was undet ectable. Subcellular fractionation demonstrates that a substantial amo unt of the VAMP-2 (24-36%) is associated with dense core, catecholamin e-containing granules (DCGs). This was confirmed by immunofluorescence microscopy. The L chain of tetanus neurotoxin, known to inhibit granu le mediated secretion in permeabilized PC12 cells, as well as botulinu m neurotoxins F and G, effectively cleaved DCG-associated VAMP-2. Thes e data demonstrate that VAMP-2 is present on the secretory granules of PC12 cells.