Botulinum toxin-induced ADP-ribosylation and inhibition of exocytosis are unrelated events

AbstractThe hypothesis that inhibition of secretion by botulinum neurotoxin type D occurs by an intracellular process involving ADP-ribosylation has been directly tested by measuring both the extent of inhibition of secretion and of ADP-ribosylation in the same cells. Although the inhibitory effect of unpurified toxin closely parallels intracellular ribosylation, the two events are clearly unrelated, as using purified D and C3 toxins together with their antibodies, each of these events can be either stimulated or inhibited independently of each other