We have developed a secretion assay composed of semi-intact synaptosom
es from which transmitter release is optimally evoked by micromolar Ca
2+ in the presence of cytosol. Transmitter release from this preparati
on reconstitutes known characteristics of regulated exocytosis and is
accompanied by a marked decrease in synaptic vesicles. The assay is us
eful in characterizing the components known to be involved in transmit
ter release, and should also facilitate the identification of addition
al factors that are important for this process. (C) 1998 Academic Pres
s.