|PROSITE documentation PDOC50892 [for PROSITE entry PS50892]|
The process of vesicular membrane fusion in eukaryotic cells depends on a conserved fusion machinery called SNARE (soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptors). In the process of vesicle docking, proteins present on the vesicle (v-SNARE) have to bind to their counterpart on the target membrane (t-SNARE) to form a core complex that can then recruit the soluble proteins NSF and SNAP. This so called fusion complex can then disassemble after ATP hydrolysis mediated by the ATPase NSF in a process that leads to membrane fusion and the release of the vesicle contents. v-SNAREs include proteins homologous to synaptobrevin [1,2,3].
Structurally the SNARE complex is generally a four-helix bundle comprised of three coiled-coil-forming domains from t-SNAREs (see <PDOC50192>) and one from v-SNARE (see <PDB:1GL2>). Although sequence similarity in the t- and v-SNARE coiled-coil homology domains are low there is a striking conservation of the so-called heptad repeat that is of central importance in forming a coiled-coil structure. In a coiled-coil motif, seven residues constitute a canonical heptad and are designated 'a' through 'g', with 'a' and 'd' being occupied by hydrophobic residues. The association of the four α-helices in the SNARE fusion complex structure produces highly conserved layers of interacting amino acid side chains in the center of the four-helix bundle. The center of the bundle is made up of 15 hydrophobic layers from the 'a' and 'd' positions of the heptad repeats of the coiled-coil-forming domains, whereas the central 'ionic' layer is highly conserved and polar in nature, containing a glutamine residue in the three t-SNAREs and an arginine in the v-SNARE, hence the classification of v- and t-SNAREs as R- and Q-SNAREs, respectively. The v-SNARE coiled-coil homology domain is around 60 amino acids in length [1,2,3].
The profile we developed cover the entire v-SNARE coiled-coil homology domain.Last update:
December 2002 / New entry.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Terrian D.M. White M.K.|
|Title||Phylogenetic analysis of membrane trafficking proteins: a family reunion and secondary structure predictions.|
|Source||Eur. J. Cell Biol. 73:198-204(1997).|
|2||Authors||Fasshauer D. Sutton R.B. Brunger A.T. Jahn R.|
|Title||Conserved structural features of the synaptic fusion complex: SNARE proteins reclassified as Q- and R-SNAREs.|
|Source||Proc. Natl. Acad. Sci. U.S.A. 95:15781-15786(1998).|
|3||Authors||Scales S.J. Hesser B.A. Masuda E.S. Scheller R.H.|
|Title||Amisyn, a novel syntaxin-binding protein that may regulate SNARE complex assembly.|
|Source||J. Biol. Chem. 277:28271-28279(2002).|