Synaptobrevins ( synaptobrevin isotypes 1-2) are small integral membrane proteins of secretory vesicles with molecular weight of 18 kilodalton (kDa) that are part of the vesicle-associated membrane protein (VAMP) family.[
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Synaptobrevin is one of the SNARE proteins involved in formation of the SNARE complexes.
Structure
Out of four α-helices of the core SNARE complex one is contributed by synaptobrevin, one by
syntaxin, and two by SNAP-25 (in neurons).
Function
SNARE proteins are the key components of the molecular machinery that drives fusion of membranes in
exocytosis. Their function however is subject to fine-tuning by various regulatory proteins collectively referred to as
SNARE masters.
Classification
In the Q/R
nomenclature for organizing SNARE proteins, VAMP/synaptobrevin family members are classified as
R-SNAREs, so named for the presence of an
arginine at a specific location within the
primary sequence of the protein (as opposed to the SNAREs of the target membrane, which contain a
glutamine and are so named
). Synaptobrevin is classified as a V-SNARE in the V/T nomenclature, an alternative classification scheme in which SNAREs are classified as V-SNAREs and T-SNAREs for their localization to vesicles and target membranes, respectively.
[Juan S. Bonifacino and Benjamin S. Glick. "The Mechanisms of Vesicle Budding and Fusion." Cell, Vol. 116, 153–166, January 23, 2004,]
Clinical significance
Synaptobrevin is degraded by
tetanospasmin, a protein derived from the bacterium
Clostridium tetani, which causes
tetanus. A related bacterium,
Clostridium botulinum, produces the
botulinum toxin. Various botulinum toxin serotypes exist that each cleave specific peptide bonds of specific neuronal SNARE proteins, and synaptobrevin is this target protein for several of the serotypes.
Human proteins containing this domain
SEC22A; SEC22B; VAMP1; VAMP2; VAMP3; VAMP4; VAMP5; VAMP7; VAMP8; YKT6;
References and notes
External links
