title: Sequence and electrophysiological characterization of two insect-selective excitatory toxins from the venom of the Chinese scorpion Buthus martensi.
abstract: The two insecticidal peptides Bm32-VI and Bm33-I, isolated from the venom of the Chinese scorpion Buthus martensi induce paralytical symptoms typical of insect contractive toxins. They show, respectively, 74% and 77% homology with AaIT from Androctonus australis, comparable insecticidal activity and no vertebrate toxicity. Under voltage-clamp conditions, both toxins induced (1) an increased fast Na(+) current, (2) a shift in voltage dependence of Na(+) current activation, (3) the occurrence of a delayed current, and (4) a slow development of a holding current. Increased Na(+) conductance at negative potential values is responsible for axonal hyperexcitability and the contractive paralysis of insect prey.
authors.affiliation: Suntory Institute for Bioorganic Research, Wakayamadai, Osaka, Japan. pescoubas@compuserve.com
authors.forename: P
authors.initials: P
authors.lastname: Escoubas
authors.forename: M
authors.initials: M
authors.lastname: Stankiewicz
authors.forename: T
authors.initials: T
authors.lastname: Takaoka
authors.forename: M
authors.initials: M
authors.lastname: Pelhate
authors.forename: R
authors.initials: R
authors.lastname: Romi-Lebrun
authors.forename: F Q
authors.initials: FQ
authors.lastname: Wu
authors.forename: T
authors.initials: T
authors.lastname: Nakajima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D003058:Cockroaches; D004594:Electrophysiology; D007276:Injections, Intraventricular; D007306:Insecticides / Q000737:chemistry* / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D012604:Scorpion Venoms / Q000737:chemistry* / Q000494:pharmacology; D012605:Scorpions / Q000737:chemistry*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018675:Toxicity Tests
chemical_list: D007306:Insecticides; D012604:Scorpion Venoms