a scorpion α-insect toxin‚ which prolongs the evoked action potential by an inhibition of sodium current inactivation in insects and mammals. Lqh α- IT serves as a marker for receptor site-3 on insect and mammalian sodium channels (2‚ 4-6).

65-amino acid polypeptide with 4 disulfide bridges produced in E.coli (1‚2)‚ originally from Leiurus quinquestriatus hebraeus venom (3).

Lqh α- IT is highly toxic to insects; it also has a strong toxicity to mice by subcutaneous injection (but very weak by intraventricular route (4)). Lqh aIT causes an extreme prolongation of the action potential in both cockroach giant axon and rat skeletal muscle preparations as a result of the slowing and incomplete inactivation of the sodium currents (3‚4). LqhaIT is very active on insect and skeletal muscle sodium channels expressed in Xenopus oocytes but is very weak on rat brain IIa channels (5‚6).

1. Tugarinov et al., (1997) Biochemistry 36,2414-2424. 2.
2. Zilberberg et al., (1997) J. Biol. Chem. 272, 14810-14818.
3. Eitan et al., Biochemistry (1990). 29:5941-5947
4. Gordon et al., J. Biol. Chem. (1996) 271:8034-8045
5. Karbat et al., (2004) J, Biol. Chem. 279, 31679-31686.
6. Gilles et al., (2000) Eur. J. Neurosci. 12, 2823-2832