Scorpion venoms contain groups of neurotoxins active specifically on mammals or insects. These peptide toxins can be classified into two main categories based on their molecular sizes and pharmacological actions. Short-chain toxins, composed of 30-40 amino acid residues with 3 or 4 disulfide bonds, affect mainly potassium or chloride channels, while long-chain toxins, composed of 60-70 amino acid residues with 4 disulfide bonds, affect mainly sodium channels and can be divided into two groups, the alpha and beta toxins. The alpha toxins bind in a voltage-dependent manner and modulate the sodium current inactivation stage, whereas binding of beta toxins is voltage-independent and interferes with the sodium current activation stage. The beta toxin class includes the groups of excitatory and depressant toxins, which differ in their mode of action and are highly specific against insects. They can selectively bind to the corresponding channels on the membrane of excitable cells, thus impairing the initial rapid depolarization phase of the action potential in nerve and muscle, resulting in neurotoxicity. This family contains the long-chain alpha and beta toxins from scorpion venom.
Jiyao W et al.(2023). "The conserved domain database in 2023.",