Fig. 4. Expression of BoNT/E-resistant SNAP-25A mutants does not inhibit the cleavage of endogenous SNAP-25 by the toxin. (A) Homogenates of wild-type Neuro2A cells (lane 1) and of cells stably expressing BoNT/E, the G14 cells (lane 2-4). G14 cells were transiently transfected with POMC-ß-Gal together with either pcB7 (lane 2) or SNAP-25A/ER-pcB7 (lane 3) or Delta-SNAP-25A/ER-pcB7 (lane 4). Homogenates of cells expressing the indicated constructs were electrophoresed on 13% SDS-PAGE gels, and western blots were probed with anti-SNAP-25 antibody. The arrowhead indicates the endogenous SNAP-25. (B) Release of ß-Gal activity under basal conditions from G14 cells and wild-type Neuro2A cells transfected with POMC-ß-Gal construct. The release is calculated as a percentage of the total ß-Gal activity in the cells.