Soluble N-ethylmaleimide attachment protein receptor (SNARE) proteins are a family of membrane-associated proteins characterised by an alpha-helical coiled-coil domain called the SNARE motif . These proteins are classified as v-SNAREs and t-SNAREs based on their localisation on vesicle or target membrane; another classification scheme defines R-SNAREs and Q-SNAREs, as based on the conserved arginine or glutamine residue in the centre of the SNARE motif. SNAREs are localised to distinct membrane compartments of the secretory and endocytic trafficking pathways, and contribute to the specificity of intracellular membrane fusion processes.
The t-SNARE domain consists of a 4-helical bundle with a coiled-coil twist. The SNARE motif contributes to the fusion of two membranes. SNARE motifs fall into four classes: homologues of syntaxin 1a (t-SNARE), VAMP-2 (v-SNARE), and the N- and C-terminal SNARE motifs of SNAP-25. It is thought that one member from each class interacts to form a SNARE complex.
The SNARE motif represented in this entry is found in the N-terminal domains of certain syntaxin family members: syntaxin 1a, which is required for neurotransmitter release, syntaxin 6, which is found in endosomal transport vesicles , yeast Sso1p , and Vam3p, a yeast syntaxin essential for vacuolar fusion . The SNARE motifs in these proteins share structural similarity, despite having a low level of sequence similarity.