Fig. 5. BoNT/C1 incompletely cleaves SNAP25 and syntaxin I, and partially inhibits Ca²⁺-dependent CGRP release evoked by three stimuli. TGNs were treated with BoNT/C1, and release of CGRP was assayed and western blotting performed. Results were calculated as described for Fig. 4 relative to Sbr I and Sbr II control. (A) Partial cleavage of SNAP25 by BoNT/C1, visualised with the IgG used in Fig. 4. Decrease in syntaxin I was revealed with an antibody only reactive with this intact SNARE. Syntaxin II and, especially, syntaxin III, proved difficult to quantify and, thus, cleavage by toxin was not detectable. (B) Dose-response curves for BoNT/C1-induced cleavage of SNAP25 () and syntaxin I (). (C) BoNT/C partially inhibits CGRP release evoked by 60 mM K⁺ (), 0.1 µM bradykinin () or 1 µM capsaicin (). Data plotted are the mean ± s.e.m.; n3.