1fh3

Structural highlights

Function

[SCL3_LEIQH] Binds voltage-independently at site-3 of sodium channels and inhibits the inactivation of the activated channels, thereby blocking neuronal transmission. The dissociation is voltage-dependent. This alpha-like toxin is highly toxic to insects and competes with LqhaIT on binding to insect sodium channels. Differs from classical anti-mammalian alpha-toxins as it inhibits sodium channel inactivation in cell bodies of hippocampus brain neurons, on which the anti-mammalian Lqh2 is inactive, and is unable to affect Nav1.2 in the rat brain, on which Lqh2 is highly active. Moreover, its pharmacological properties are unique in that its binding affinity for insect channels drops >30-fold at pH 8.5 versus pH 6.5, and its rate of association with receptor site-3 on both insect and mammalian sodium channels is 4-15-fold slower compared with LqhaIT and Lqh2.^{[1] [2] [3] [4] [5]}

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

References

1. ↑ Sautiere P, Cestele S, Kopeyan C, Martinage A, Drobecq H, Doljansky Y, Gordon D. New toxins acting on sodium channels from the scorpion Leiurus quinquestriatus hebraeus suggest a clue to mammalian vs insect selectivity. Toxicon. 1998 Aug;36(8):1141-54. PMID:9690781
2. ↑ Chen H, Gordon D, Heinemann SH. Modulation of cloned skeletal muscle sodium channels by the scorpion toxins Lqh II, Lqh III, and Lqh alphaIT. Pflugers Arch. 2000 Feb;439(4):423-32. PMID:10678738
3. ↑ Gilles N, Blanchet C, Shichor I, Zaninetti M, Lotan I, Bertrand D, Gordon D. A scorpion alpha-like toxin that is active on insects and mammals reveals an unexpected specificity and distribution of sodium channel subtypes in rat brain neurons. J Neurosci. 1999 Oct 15;19(20):8730-9. PMID:10516292
4. ↑ Chen H, Heinemann SH. Interaction of scorpion alpha-toxins with cardiac sodium channels: binding properties and enhancement of slow inactivation. J Gen Physiol. 2001 Jun;117(6):505-18. PMID:11382802
5. ↑ Karbat I, Kahn R, Cohen L, Ilan N, Gilles N, Corzo G, Froy O, Gur M, Albrecht G, Heinemann SH, Gordon D, Gurevitz M. The unique pharmacology of the scorpion alpha-like toxin Lqh3 is associated with its flexible C-tail. FEBS J. 2007 Apr;274(8):1918-31. Epub 2007 Mar 9. PMID:17355257 doi:http://dx.doi.org/EJB5737