FIGURE 1.

Ligand‐receptor–binding model for toxin and its corresponding receptor. Bulk botulinum toxin is complexed with neurotoxin‐associated complexing Proteins and formulated with human serum albumin in the vial before becoming free type A neurotoxin (150 kDa) in a neutral to basic environment, such as upon reconstitution. Following injection, the complex‐free neurotoxin binds to 2 extraneuronal receptors, allowing bound neurotoxin to undergo endocytosis. The translocated neurotoxin is able to move intracellularly across the neuronal cytosol to the intracellular target, SNAP‐25, inducing proteolysis. Proteolysis of SNAP‐25 induces blockade of acetylcholine release into the postsynaptic neuromuscular junction, resulting in muscular paralysis. (Adapted from Simpson ⁶² and Lebeda et al ¹⁴⁸ )