SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins consist of coiled-coil helices (called SNARE motifs) which mediate the interactions between SNARE proteins, and a transmembrane domain. The SNARE complex mediates membrane fusion, important for trafficking of newly synthesized proteins, recycling of pre-existing proteins and organelle formation. SNARE proteins are classified into four groups, Qa-, Qb-, Qc- and R-SNAREs, depending on whether the residue in the hydrophilic center layer of the four-helical bundle is a glutamine (Q) or arginine (R). Qa-, Qb- and Qc-SNAREs are localized to target organelle membranes, while R-SNARE is localized to vesicle membranes. They form unique complexes consisting of one member of each subgroup, that mediate fusion between a specific type of vesicles and their target organelle. Their SNARE motifs form twisted and parallel heterotetrameric helix bundles.
Comment:formed by the cytoplasmic domain of synaptobrevin-II, the carboxy H3 domain of syntaxin-1A, and the amino- and carboxy-terminal domains of SNAP-25B which forms a shallow groove for specific binding sites
Comment:acts as a water tight shield for the ionic interactions in the 0 layer protecting it from the surrounding solvent
Comment:may stabilize the synaptic fusion complex by enhancing electrostatic interactions within the ionic layer
Structure:1SFC_J, Rattus norvegicus composed of layers -1, +1, and +2
Jiyao W et al.(2023). "The conserved domain database in 2023.",