TL;DR: The existence of numerous SNARE-related proteins, each apparently specific for a single kind of vesicles or target membrane, indicates that NSF and SNAPs may be universal components of a vesicle fusion apparatus common to both constitutive and regulated fusion (including neurotransmitter release), in which the SNAREs may help to ensure vesICLE-to-target specificity.
Abstract: The N-ethylmaleimide-sensitive fusion protein (NSF) and the soluble NSF attachment proteins (SNAPs) appear to be essential components of the intracellular membrane fusion apparatus. An affinity purification procedure based on the natural binding of these proteins to their targets was used to isolate SNAP receptors (SNAREs) from bovine brain. Remarkably, the four principal proteins isolated were all proteins associated with the synapse, with one type located in the synaptic vesicle and another in the plasma membrane, suggesting a simple mechanism for vesicle docking. The existence of numerous SNARE-related proteins, each apparently specific for a single kind of vesicle or target membrane, indicates that NSF and SNAPs may be universal components of a vesicle fusion apparatus common to both constitutive and regulated fusion (including neurotransmitter release), in which the SNAREs may help to ensure vesicle-to-target specificity.
TL;DR: In this article, the authors uncovered the general protein apparatus used by all eukaryotes for intracellular transport, including secretion and endocytosis, and for triggered exocytotic of hormones and neurotransmitters.
Abstract: Recent advances have uncovered the general protein apparatus used by all eukaryotes for intracellular transport, including secretion and endocytosis, and for triggered exocytosis of hormones and neurotransmitters. Membranes are shaped into vesicles by cytoplasmic coats which then dissociate upon GTP hydrolysis. Both vesicles and their acceptor membranes carry targeting proteins which interact specifically to initiate docking. A general apparatus then assembles at the docking site and fuses the vesicle with its target.
TL;DR: It is reported that in the absence of SNAP and NSF, these three SNAREs form a stable complex that can also bind synaptotagmin, suggesting that synapttagmin operates as a "clamp" to prevent fusion from proceeding in the absent of a signal.
TL;DR: The molecular mechanisms of calcium-dependent exocytosis of synaptic vesicles mediates the release of neurotransmitters are surveyed in an attempt to functionally integrate the key proteins into the emerging picture of the neuronal fusion machine.
Abstract: Calcium-dependent exocytosis of synaptic vesicles mediates the release of neurotransmitters. Important proteins in this process have been identified such as the SNAREs, synaptotagmins, complexins, Munc18 and Munc13. Structural and functional studies have yielded a wealth of information about the physiological role of these proteins. However, it has been surprisingly difficult to arrive at a unified picture of the molecular sequence of events from vesicle docking to calcium-triggered membrane fusion. Using mainly a biochemical and biophysical perspective, we briefly survey the molecular mechanisms in an attempt to functionally integrate the key proteins into the emerging picture of the neuronal fusion machine.
TL;DR: Two distinct roles of [Ca(2+)] are proposed in vesicle recruitment: one accelerating "molecular priming" (vesicle docking and the buildup of a release machinery), the other promoting the tight coupling between releasable vesicles and Ca(2+) channels.