New toxins acting on sodium channels from the scorpion Leiurus quinquestriatus hebraeus suggest a clue to mammalian vs insect selectivity
Autor: | Sandrine Cestèle, Yvon Doljansky, Pierre Sautière, Arlette Martinage, Hervé Drobecq, Charles Kopeyan, Dalia Gordon |
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Rok vydání: | 1998 |
Předmět: |
animal structures
Leiurus Molecular Sequence Data Neurotoxins Scorpion Scorpion Venoms Cockroaches Venom Biology Toxicology medicine.disease_cause complex mixtures Sodium Channels Mice Species Specificity biology.animal medicine Animals Amino Acid Sequence Amino Acids Cockroach Scorpion toxin Sequence Homology Amino Acid Ecology Toxin Sodium channel biology.organism_classification Rats Mice Inbred C57BL Biochemistry Buthus occitanus Synaptosomes |
Zdroj: | Toxicon. 36:1141-1154 |
ISSN: | 0041-0101 |
Popis: | Two new toxins were purified from Leiurus quinquestriatus hebraeus (Lqh) scorpion venom, Lqh II and Lqh III. Lqh II sequence reveals only two substitutions, as compared to AaH II, the most active scorpion alpha-toxin on mammals from Androctounus australis Hector. Lqh III shares 80% sequence identity with the alpha-like toxin Bom III from Buthus occitanus mardochei. Using bioassays on mice and cockroach coupled with competitive binding studies with 125I-labeled scorpion alpha-toxins on rat brain and cockroach synaptosomes, the animal selectivity was examined. Lqh II has comparable activity to mammals as AaH II, but reveals significantly higher activity to insects attributed to its C-terminal substitution, and competes at low concentration for binding on both mammalian and cockroach sodium channels. Lqh II thus binds to receptor site 3 on sodium channels. Lqh III is active on both insects and mammals but competes for binding only on cockroach. The latter indicates that Lqh III binds to a distinct receptor site. Thus, Lqh II and Lqh III represent two different scorpion toxin groups, the alpha- and alpha-like toxins, respectively, according to the structural and pharmacological criteria. These new toxins may serve as a lead for clarification of the structural basis for insect vs mammal selectivity of scorpion toxins. |
Databáze: | OpenAIRE |
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