OD1, the first toxin isolated from the venom of the scorpion Odonthobuthus doriae active on voltage-gated Na(+) channels
In this study, we isolated and pharmacologically characterized the first a-like toxin from the venom of the scarcely studied Iranian scorpion Odonthobuthus doriae. The toxin was termed OD1 and its primary sequence was determined: GVRDAYIADDKNCVYTCASNGYCNTECTKNGAESGYCQWIGRYGNACWCIKLPDEVPIRIPGKCR. Using the two-electrode voltage clamp technique, the pharmacological effects of OD1 were studied on three cloned voltage-gated Na(+) channels expressed in Xenopus laevis oocytes (Na(v)1.2/beta(1) Na(v)1.5/beta(1), para/tipE). The inactivation process of the insect channel, para/tipE, was severely hampered by 200 nM of OD1 (EC(50) = 80 +/- 14 nM) while Na(v)1.2/beta(1) still was not affected at concentrations up to 5 mu M. Na(v)1.5/beta(1) was influenced at micromolar concentrations. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.