Gordon D, Zlotkin E
Hebrew University of Jerusalem, Department of Cell and Animal Biology, Israel.
FEBS Lett. 1993 Jan 4;315(2):125-8. doi: 10.1016/0014-5793(93)81147-r.
The insect-specific Lqh alpha IT toxin resembles alpha scorpion toxins affecting mammals by its amino acid sequence and effects on sodium conductance. The present study reveals that Lqh alpha IT does not bind to rat brain membranes and possesses in locust neuronal membranes a single class of high affinity (Kd = 1.06 +/- 0.15 nM) and low capacity (Bmax = 0.7 +/- 0.19 pmol/mg protein) binding sites. The latter are: (1) distinct from binding sites of other sodium channel neurotoxins; (2) inhibited by sea anemone toxin II; (3) cooperatively interacting with veratridine; (4) not dependent on membrane potential, in contrast to the binding sites of alpha toxins in vertebrate systems. These data suggest the occurrence of (a) conformational-structural differences between insect and mammal sodium channels and (b) the animal group specificity and pharmacological importance of the alpha scorpion toxins.
昆虫特异性LqhαIT毒素在氨基酸序列以及对钠电导的影响方面类似于影响哺乳动物的α-蝎毒素。本研究表明，LqhαIT不与大鼠脑膜结合，而在蝗虫神经元膜中具有一类单一的高亲和力（Kd = 1.06±0.15 nM）和低容量（Bmax = 0.7±0.19 pmol/mg蛋白质）结合位点。后者具有以下特点：（1）与其他钠通道神经毒素的结合位点不同；（2）被海葵毒素II抑制；（3）与藜芦定协同相互作用；（4）与脊椎动物系统中α毒素的结合位点不同，不依赖于膜电位。这些数据表明：（a）昆虫和哺乳动物钠通道之间存在构象结构差异；（b）α-蝎毒素具有动物群体特异性和药理学重要性。
