SNARE Complex

SNARE COMPLEX : machinery for synaptic vesicle fusion -SYNAPTOTAGMIN, SYNAPTOPBREVIN, SNAP-25, SYNTAXIN 1, COMPLEXIN PRESYNAPTIC TERMINAL ACTIVE ZONE DOCKING COMPLEXIN SYNAPTIC SNAPTOTAGMIN VESICLE SYNAPTOBREVIN PRIMING FUSION SYNTAXIN 1 SYNAPTIC VESICLE SNAP-25 SYNAPTIC CLEFT Synaptic vesicles move down the axon and dock at the active zone of the presynaptic terminal. After docking, vesicles are primed so they can be rapidly released into the synaptic cleft. During this priming stage, complexin acts as a fusion clamp by binding to the SNARE complex. When calcium binds to synaptotagmin on the synaptic vesicle, synaptotagmin displaces complexin from the SNARE complex, triggering vesicle fusion. With the help of SNAP-25 and syntaxin-1 on the presynaptic membrane, the vesicle fusion occurs and neurotransmitter is released into the synaptic cleft. VESICLE FUSION IS A TIGHTLY REGULATED PROCESS WHAT'S THE IMPLICATION? The SNARE complex plays a key role in synaptic communication. Disruption of its activity with toxins like botulinum and tetanus blocks the exocytosis of synaptic vesicles and ultimately causes paralysis. Many neurological diseases, including schizophrenia and epilepsy, are caused by disrupted synaptic transmission, so this remains an intense area of research. Sources: Carr Cand Munson M. Tag team action at the synapse. EMB0 reports (2007) 8, 834-838. Südhof TC, Rothman JE. Membrane fusion: Grappling with SNARE and SM proteins. Science (2009) 323:474-477. Graphic by Jooyeun Lee SNARE COMPLEX : machinery for synaptic vesicle fusion -SYNAPTOTAGMIN, SYNAPTOPBREVIN, SNAP-25, SYNTAXIN 1, COMPLEXIN PRESYNAPTIC TERMINAL ACTIVE ZONE DOCKING COMPLEXIN SYNAPTIC SNAPTOTAGMIN VESICLE SYNAPTOBREVIN PRIMING FUSION SYNTAXIN 1 SYNAPTIC VESICLE SNAP-25 SYNAPTIC CLEFT Synaptic vesicles move down the axon and dock at the active zone of the presynaptic terminal. After docking, vesicles are primed so they can be rapidly released into the synaptic cleft. During this priming stage, complexin acts as a fusion clamp by binding to the SNARE complex. When calcium binds to synaptotagmin on the synaptic vesicle, synaptotagmin displaces complexin from the SNARE complex, triggering vesicle fusion. With the help of SNAP-25 and syntaxin-1 on the presynaptic membrane, the vesicle fusion occurs and neurotransmitter is released into the synaptic cleft. VESICLE FUSION IS A TIGHTLY REGULATED PROCESS WHAT'S THE IMPLICATION? The SNARE complex plays a key role in synaptic communication. Disruption of its activity with toxins like botulinum and tetanus blocks the exocytosis of synaptic vesicles and ultimately causes paralysis. Many neurological diseases, including schizophrenia and epilepsy, are caused by disrupted synaptic transmission, so this remains an intense area of research. Sources: Carr Cand Munson M. Tag team action at the synapse. EMB0 reports (2007) 8, 834-838. Südhof TC, Rothman JE. Membrane fusion: Grappling with SNARE and SM proteins. Science (2009) 323:474-477. Graphic by Jooyeun Lee