Androctonus australis hector alpha-toxin (Aah alpha-toxin) (Aah alpha-toxin)

Androctonus australis hector (Aah) alpha-toxins are a group of highly potent neurotoxic peptides found in the venom of the North African scorpion. These toxins, particularly the well-studied Aah II, are the primary drivers of toxicity in humans following envenomation (UniProt: P01490). They function by binding with high affinity to neurotoxin receptor site 3 on voltage-gated sodium (Nav) channels, primarily in the nervous and muscular systems (Cestèle & Catterall, 2000). This binding slows the inactivation of the sodium channel, leading to prolonged depolarization and repetitive firing of action potentials, which manifests clinically as an autonomic storm involving massive release of catecholamines and acetylcholine (Martin-Eauclaire et al., 2019). Because of their lethal potency, these toxins are the primary targets for the development of therapeutic antivenoms and next-generation neutralizing agents like nanobodies. Understanding their structure-function relationship is critical for designing effective treatments against scorpionism in endemic regions.

Other names

Aah IIAah IAlpha-mammal toxinScorpion toxin IIButhidae alpha-neurotoxinSite 3 toxin

The toxins bind to neurotoxin receptor site 3 on the extracellular loops of voltage-gated sodium channels (Nav), specifically hindering the movement of the S4 segment in domain IV. This action slows the inactivation process of the channel, leading to prolonged sodium influx and persistent depolarization of excitable cells.