synaptobrevin

Synaptobrevin, also known as vesicle-associated membrane protein (VAMP), is a family of small, membrane-anchored proteins located on the membranes of secretory vesicles. In mammals, the major neuronal isoforms are synaptobrevin-1 (VAMP1) and synaptobrevin-2 (VAMP2), while a more broadly expressed form, synaptobrevin-3 (VAMP3), participates in other secretory pathways. These proteins are part of the SNARE (soluble N-ethylmaleimide–sensitive factor attachment protein receptor) family that mediates membrane fusion.

Synaptobrevin functions as a vesicle (v-)SNARE. It forms a complex with plasma membrane SNAREs, typically syntaxin-1 and SNAP-25, to create the SNARE complex that brings vesicle and plasma membranes into close contact. The assembly of this complex drives rapid, calcium-triggered membrane fusion and neurotransmitter release at chemical synapses. After fusion, the SNARE complex is disassembled by N-ethylmaleimide–sensitive factor (NSF) and other cofactors, allowing vesicle recycling.

Structurally, synaptobrevin has a cytosolic SNARE motif essential for complex formation and a single C-terminal transmembrane helix that anchors it to the vesicle membrane. The protein's vesicular localization and SNARE interactions position it as a key driver of vesicle fusion during exocytosis.

Physiologically, synaptobrevin is critical for both evoked and spontaneous neurotransmitter release. Disruption of synaptobrevin function impairs synaptic transmission, and genetic or pharmacological perturbations can alter release probability. Toxins such as botulinum and tetanus neurotoxins target SNARE proteins, including synaptobrevin, to block neurotransmitter release.