Androctonus australis hector venom toxins (Aah toxins)

Androctonus australis hector (Aah) venom toxins are a potent collection of neurotoxic polypeptides derived from the North African fat-tailed scorpion. These toxins, most notably the alpha-toxin Aah II, are highly lethal to mammals because they specifically target and disrupt the function of voltage-gated sodium (Nav) channels in the nervous system (UniProt P01490). By binding to receptor site 3 on these channels, the toxins inhibit the inactivation phase of the action potential, causing prolonged cellular depolarization and a massive, systemic release of neurotransmitters known as an autonomic storm (PubMed: 11566465). This physiological disruption leads to severe clinical manifestations such as pulmonary edema, hypertension, and heart failure. While these toxins are the primary causative agents of scorpionism, they are not therapeutic targets in the traditional sense; rather, they are the targets of neutralizing antibodies in antivenom therapy (PubChem). Furthermore, they serve as critical pharmacological tools in research for mapping the structural and functional domains of ion channels.

Other names

Aah venomNorth African fat-tailed scorpion toxinsAah IAah IIAah IIIAah IVScorpion alpha-toxinsScorpion neurotoxins

The toxins act as ligands that bind to specific sites on voltage-gated ion channels. Alpha-toxins (e.g., Aah II) bind to neurotoxin receptor site 3 of voltage-gated sodium (Nav) channels, slowing the inactivation process and leading to prolonged action potentials. Beta-toxins bind to site 4, shifting the voltage dependence of activation to more negative potentials. These actions result in persistent depolarization and massive release of endogenous neurotransmitters (catecholamines and acetylcholine).