title: Identification of two toxins from scorpion (Leiurus quinquestriatus) venom which block distinct classes of calcium-activated potassium channel.
abstract: Two polypeptide toxins from scorpion (Leiurus quinquestriatus) venom which block distinct classes of calcium-activated potassium channels have been identified and partially purified. One toxin, at 50-100 ng/ml, blocks apamin-sensitive potassium fluxes in hepatocytes and inhibits [125I]monoiodoapamin binding. The other, more basic, toxin blocks apamin-insensitive potassium fluxes in erythrocytes at 200 ng/ml and, to our knowledge, is the first toxin shown to block the erythrocyte calcium-activated potassium channel with high affinity. The possible co-identity of this latter toxin with charybdotoxin is discussed.
mesh_terms: D000818:Animals; D001030:Apamin / Q000302:isolation & purification / Q000633:toxicity; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology; D006168:Guinea Pigs; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D012604:Scorpion Venoms / Q000302:isolation & purification / Q000633:toxicity*; D012605:Scorpions
chemical_list: D007473:Ion Channels; D012604:Scorpion Venoms; D001030:Apamin; D000001:Calcimycin; D002118:Calcium