SNAREdependent

SNARE-dependent refers to membrane fusion events that are mediated by SNARE proteins. SNAREs are a family of proteins that assemble into a four-helix bundle to drive vesicle fusion with a target membrane. The term is used to distinguish SNARE-driven fusion from other fusion mechanisms that do not rely on SNAREs.

V-SNAREs on vesicles (such as VAMP/synaptobrevin) and t-SNAREs on target membranes (such as syntaxin and SNAP-25) form a trans-SNARE complex. The complex brings the two membranes into close apposition and catalyzes lipid bilayer merging. The energy stored in the assembled SNARE bundle drives the fusion process.

Regulation involves several accessory proteins. Munc18-1 regulates syntaxin availability and SNARE assembly; complexins stabilize the pre-fusion SNARE complex; synaptotagmin acts as a calcium sensor to trigger rapid fusion. After fusion, NSF and α-SNAP disassemble SNAREs for recycling and reuse.

SNARE-dependent fusion underlies most regulated secretion and intracellular trafficking in eukaryotic cells, including neurotransmitter release, hormone secretion, and trafficking through the Golgi, endosomes, and lysosomes. This fusion machinery is central to both constitutive and regulated pathways that move cargo to the cell surface or between organelles.

Pathology and research context: botulinum and tetanus toxins proteolyze SNARE proteins, causing paralysis. Mutations or dysregulation of SNARE components are linked to various neurological disorders. In vitro reconstitution and genetic models are widely used to study the mechanics and regulation of SNARE-dependent fusion, helping to illuminate fundamental aspects of cellular communication and secretion.