Tuning exocytosis for speed: fast and slow modes

Exocytic fusion reactions triggered by Ca2+ are widespread in neural, endocrine, exocrine, hemapoetic and perhaps all cell types. These processes exhibit tremendous variation in latencies to fusion following a Ca2+ rise and in rates of fusion. We review reported differences for synaptic vesicle (SV) and dense-core vesicle (DCV) exocytosis and attempt to identify key features in the molecular mechanisms of docking, priming and fusion of SVs and DCVs that may account for differences in speed. (C) 2003 Elsevier B.V All rights reserved.