# Synaptobrevin

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.
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 Q-SNAREs). 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.

## 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

* ↑ Baumert M, Maycox PR, Navone F, De Camilli P, Jahn R (February 1, 1989). "Synaptobrevin: an integral membrane protein of 18,000 daltons present in small synaptic vesicles of rat brain". EMBO J. 8 (2): 379–84. doi:10.1002/j.1460-2075.1989.tb03388.x. PMC 400817. PMID 2498078.
* ↑ Bock JB, Scheller RH (October 1999). "SNARE proteins mediate lipid bilayer fusion". Proc. Natl. Acad. Sci. U.S.A. 96 (22): 12227–9. Bibcode:1999PNAS...9612227B. doi:10.1073/pnas.96.22.12227. PMC 34255. PMID 10535902.
* ↑ Ernst JA, Brunger AT (2003). "High resolution structure, stability, and synaptotagmin binding of a truncated neuronal SNARE complex". J Biol Chem. 278 (10): 8630–6. doi:10.1074/jbc.M211889200. PMID 12496247.
* ↑ Fasshauer D, Sutton RB, Brunger AT, Jahn R (December 1998). "Conserved structural features of the synaptic fusion complex: SNARE proteins reclassified as Q- and R-SNAREs". Proc. Natl. Acad. Sci. U.S.A. 95 (26): 15781–6. Bibcode:1998PNAS...9515781F. doi:10.1073/pnas.95.26.15781. PMC 28121. PMID 9861047.
* ↑ Weber T, Zemelman BV, McNew JA, Westermann B, Gmachl M, Parlati F, Sollner TH, Rothman JE (1998). "SNAREpins: minimal machinery for membrane fusion". Cell. 92 (6): 759–72. doi:10.1016/S0092-8674(00)81404-X. PMID 9529252. S2CID 5637048.
* ↑ Juan S. Bonifacino and Benjamin S. Glick. "The Mechanisms of Vesicle Budding and Fusion." Cell, Vol. 116, 153–166, January 23, 2004,