Vesicular control of fusion pore expansion.

Exocytic post-fusion events play an important role determining the composition and quantity of cellular secretion. In particular, Ca(2+)-dependent regulation of fusion pore dilation/closure is a key regulator for fine-tuning vesicle content secretion. This requires a tight temporal and spatial integration of vesicle fusion with the PM, Ca(2+) signals and translation of the Ca(2+) signal into fusion pore dilation via auxiliary factors. Yet, it is still mostly elusive how this is achieved in slow and non-excitable secretory cells, where initial Ca(2+) signals triggering fusions will abate before onset of the post-fusion phase. New results suggest, that the vesicles themselves provide the necessary itinerary to sense and link vesicle fusion to generation of local Ca(2+) signals and fusion pore expansion.