AAA Proteins Involved in Secretion and NeurotransmissionNSF and Sec18p are soluble proteins involved in vesicle fusion during the secretory pathway. Sec18p can replace NSF in an in vitro vesicle-mediated transport system from hamster. NSF can be isolated in complexes with soluble SNAP proteins (Sec17p is the yeast homologue of alpha-SNAP) and membrane bound SNARE proteins (v-SNAREs from the membrane of the transport vesicle, t-SNAREs from the target membrane), forming the 20 S fusion particle. The specific combination of v- and t-SNARE appears to control the correct targeting of the vesicles, docking the vesicle by their direct interaction. Several pairs of v- and t-SNARE have been identified both in mammalians and in yeast. Presumably, SNAPs and NSF bind to the v-/t-SNARE complex, initiating vesicle fusion. Hydrolysis of ATP by NSF leads to disassembly of the 20 S complex and may be the trigger of membrane fusion.
The identification of several synaptic proteins (synaptobrevin/VAMP; syntaxin, SNAP-25) as SNAREs revealed that intracellular transport and neurotransmission use the same components and mechanisms.
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Last edited: March 28, 1996 by KaiFr