The Last Seconds in the Life of a Secretory Vesicle
This extract was created in the absence of an abstract.
Excerpt
Regulated exocytosis may be divided into four steps: the docking of the secretory vesicle to the plasmalemma, the “priming” of the exocytotic machinery, the triggering of exocytosis by cytosolic Ca++, and, ultimately, the fusion of the vesicle membrane to the plasmalemma. As reviewed elsewhere (Ferro-Novick and Jahn 1994; Rothmann 1994; Scheller 1995; Südhof 1995), biochemical and molecular genetic studies have made significant progress in establishing the molecular basis for some of these steps. Docking has been proposed to include the binding of a “v-SNARE” (a membrane protein in the secretory vesicle, VAMP/synaptobrevin in synaptic vesicles) to two t-SNAREs in the plasmalemma (syntaxin and SNAP-25 in presynaptic terminals; Sollner et al. 1993). v- and t-SNAREs form a stable trimeric complex with a characteristic sedimentation coefficient of 7S. Priming refers to the last Mg-ATP-dependent reaction (or reactions) in the exocytotic pathway. Exocytosis universally requires Mg-ATP, but in neuroendocrine cells, ATP hydrolysis does...
