Botulinum toxin acts on:

(Ref: KD Tripathi, 7th ed. pg. 99)Release of Ach from nerve terminals occurs in small quanta--amount contained in individual vesicles is extruded by exocytosis.Two toxins interfere with cholinergic transmission by affecting release:# Botulinum toxin inhibits release# Black widow spider toxin induces massive release and depletionBotulinum toxin# Botulinum toxin A and B are highly potent exotoxins produced by Clostridium botulinum that are responsible for 'botulism' (a type of food poisoning). These neurotoxic proteins cause long-lasting loss of cholinergic transmission by interacting with axonal proteins involved in exocytotic release of Ach.