Affinity labelling of the tetrodotoxin-binding component of the Na+ channel

Tetrodotoxin-binding sites were covalently labelled with a highly tritiated derivative of tetrodotoxin. Cross-linking experiments, using dissucinimidyl suberate, on partially purified tetrodotoxin-binding component from electroplax of Electrophorus electricus, revealed covalent labelling of a single polypeptide chain of MW 270,000.