Scorpion alpha-toxin (Alpha-ScTx)

Scorpion alpha-toxins are a class of potent neurotoxic peptides found in the venom of scorpions belonging to the Buthidae family, such as Androctonus and Centruroides [Gordon et al., 2007]. These toxins are defined by their specific high-affinity interaction with neurotoxin receptor site 3 on voltage-gated sodium channels (Nav), which are essential for action potential propagation in excitable cells [Catterall, 2012]. Mechanistically, alpha-toxins bind to the extracellular loops of the sodium channel's domain IV, effectively slowing or blocking the fast inactivation process [UniProt, 2024]. This leads to prolonged sodium influx, persistent membrane depolarization, and a massive release of neurotransmitters, resulting in the clinical syndrome known as an autonomic storm. In a therapeutic context, these toxins are the primary targets for neutralizing antivenoms, which utilize purified antibody fragments to sequester the peptides from their receptors [FDA, 2011]. Beyond their role in pathology, they serve as invaluable molecular probes for studying the structural and functional architecture of ion channels.

Other names

Alpha-scorpion toxinSite 3 sodium channel toxinButhidae neurotoxinScorpion alpha-neurotoxinAlpha-mammal toxin

Binding to neurotoxin receptor site 3 on voltage-gated sodium channels (Nav) to inhibit fast inactivation, resulting in prolonged depolarization and neuronal hyperexcitability.