1999 Volume 125 Issue 4 Pages 685-689
The membrane protein syntaxin (originally named HPC-1) is involved in vesicle trafficking and required for neurotransmitter release at nerve terminals. The presence of syntaxin on target membranes is hypothesized to confer specificity to targeting and fusion via interactions with complementary vesicle-associated proteins. To elucidate the function of syntaxin 1 A in exocytosis, HPC-1/syntaxin 1A-reduced PC12h cells (PC12h/Δsyx) that were stably transfected with a plasmid for antisense syntaxin 1 A expression were constructed. Depolarizing stimulation of PC12h/Jsyx enhanced dopamine release, compared with PC12h. There was a strong inverse correlation between syntaxin 1 A protein expression and enhancement of dopamine release. Reduction of syntaxin 1 A had no effect on increase of the cytoplasmic free Ca2+ concentration by depolarized stimulation. Moreover, PC12h/Jsyx clones similarly enhanced of exocytosis by native secretagogues. These results indicate that syntaxin 1 A has more than one function in exocytosis.
