Identification of two toxins from scorpion (Leiurus quinquestriatus) venom which block distinct classes of calcium‐activated potassium channel

摘要

>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 class="mathematics"> data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(86)81095-X/asset/equation/feb2001457938681095x-math-si1.gif?v=1&s=085285337ffc6211ba704eb739129b0f19047eea" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none">, 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 class="mathematics"> data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(86)81095-X/asset/equation/feb2001457938681095x-math-si2.gif?v=1&s=2270f2c055100f4e6bb129bab1518278ebb77004" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none"> 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.