Syntaxin Conservation

Fig. 3. Specificity and sites of cleavage of the clostridial neurotoxins. VAMP is bound to the SSV membrane through a single transmembrane domain (black box), with the majority of the protein exposed to the cytoplasm. In addition, VAMP contains an amino-terminal domain rich in proline (hatched box). SNAP-25 and syn-taxin are bound to the target membrane via palmitoylation (SNAP-25) or via a single transmembrane domain (syntaxin). TeTx and BoNT/B, D, F or G act on the conserved central portion of VAMP and release its amino-terminal part into the cytosol. The sequences indicate the peptide bonds cleaved by CNTs on rat VAMP-1 and VAMP-2. BoNT/A and E cleave SNAP-25 at the carboxyl terminus, with the release of nine and twenty-six residues peptides respectively. BoNT/C also cleaves SNAP-25 at the carboxy-terminus, and cleaves syntaxin at a single site near the cytosolic membrane surface. The action of TeTx and BoNT/B, C, D, F and G causes the release of a large portion of the cytosolic domain of VAMP and syntaxin. Conversely, only a small segment of SNAP-25 is released by the selective proteolysis of BoNT/A, C and E...

---