The Mammalian Neuromuscular Junction as a Target Tissue for Protein Toxins that Block Exocytosis
There are two major classes of protein toxins that act selectively on motor nerve endings to block exocytosis, these being clostridial neurotoxins and phospholipase A2 neurotoxins. There is a considerable amount of information about the sequence of events in clostridial neurotoxin-induced blockade of transmitter release.1-3 Pharmacological, morphological and related studies indicate that botulinum neurotoxin and tetanus toxin proceed through a series of three steps to produce their poisoning effects.1,4 There is a membrane binding step, an internalization step, and an intracellular poisoning step. By contrast, much less is known about the sequence of events in phospholipase A2 neurotoxin-induced blockade of acetylcholine release. For example, it has not been established whether these toxins act at the cell surface, within the membrane, or in the cytosol.
KeywordsSialic Acid Botulinum Toxin Sialic Acid Residue Botulinum Neurotoxin Tetanus Toxin
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