title: Inhibition of human Kv3.1 current expressed in Xenopus oocytes by the toxic venom fraction of Androctonus australis hector.
abstract: AahG50, the toxic fraction of Androctonus australis hector venom, was studied on human Kv3.1 channels activation, stably expressed in Xenopus oocytes using the two-electrode voltage clamp technique. AahG50 reduced Kv3.1 currents in a reversible concentration-dependent manner, with an IC50 value and a Hill coefficient of 40.4 ± 0.2 μg/ml and 1.3 ± 0.05, respectively. AahG50 inhibited IKv3.1 without modifying the current activation kinetics. The AahG50-induced inhibition of Kv3.1 channels was voltage-dependent, with a gradual increase at lower concentrations and over the voltage range of channels opening. However, at higher concentrations, the inhibition exhibited voltage dependence only in the first range of channels opening from -20 to +10 mV, but demonstrates a low degree of voltage-dependence when channels are fully activated. In the literature, toxins have previously been isolated from AahG50, KAaH1 and KAaH2 and were reported not to have any effect on IKv3.1. The present article's findings suggest that AahG50 may contain a peptidic component active on Kv3.1 channels, which inhibits IKv3.1 in a selective manner.
authors.affiliation: Laboratoire des Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, BP 74, 1002, Tunis, Tunisia, cheikh_amani@yahoo.com.
authors.forename: Amani
authors.initials: A
authors.lastname: Cheikh
authors.forename: Rym
authors.initials: R
authors.lastname: Benkhalifa
authors.forename: Zied
authors.initials: Z
authors.lastname: Landoulsi
authors.forename: Imen
authors.initials: I
authors.lastname: Chatti
authors.forename: Mohamed El
authors.initials: ME
authors.lastname: Ayeb
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D009865:Oocytes / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000494:pharmacology*; D012604:Scorpion Venoms / Q000737:chemistry / Q000494:pharmacology*; D051670:Shaw Potassium Channels / Q000037:antagonists & inhibitors*; D014162:Transfection; D014982:Xenopus laevis
chemical_list: C489597:KCNC1 protein, human; D010446:Peptide Fragments; D026902:Potassium Channel Blockers; D012604:Scorpion Venoms; D051670:Shaw Potassium Channels