ABSTRACT
Sodium channels are essential for the function of excitable cells. When certain toxins, such as tetrodotoxin, specifically block the Na+ channel, then this may result in severe neurotoxicity.
Tetrodotoxin (TTX) is a potent neurotoxin found in the ovary, intestine and liver of the puffer fish. Interestingly, the fish are not able to synthesize TTX by themselves; instead, they accumulate TTX which is produced by marine bacteria. Puffer fish themselves are resistant to the bacterial toxin because they feature a mutation in the biomolecule to which TTX normally binds with high affinity (the Na+ channels); TTX is unable to bind to the mutated form of the Na+ channel.
