Zorec R, Tester M, Macek P, Mason W T
Institute of Pathophysiology, University of Ljubljana, Yugoslavia.
J Membr Biol. 1990 Dec;118(3):243-9. doi: 10.1007/BF01868608.
Equinatoxin II is a 20-kDa basic protein isolated from the sea anemone Actinia equina. The aim of our work was to investigate the primary molecular basis for the cytotoxic effects of equinatoxin II in two model systems: single bovine lactotrophs and planar lipid bilayers. Previous work has shown that equinatoxin II produces rapid changes in cell morphology, which are dependent on external calcium. It has also been reported that addition of equinatoxin II increases membrane electrical conductance, which suggests that the cytotoxic action of equinatoxin II involves an increase in the permeability of membranes to Ca2+. Extensive changes in cytosolic Ca2+ activity are thought to invoke irreversible changes in cell physiology and morphology. In this paper, we show that morphological changes brought about by equinatoxin II in bovine lactotrophs are associated with a rapid rise in cytosolic Ca2+ activity, monitored with a fura-2 video imaging apparatus. Moreover, incorporation of equinatoxin II into planar lipid bilayers produces Ca2+ permeable ion channels. This suggests that the mode of equinatoxin II cytotoxicity involves the formation of cation (Ca2+) permeable channels in cell membranes.
海葵毒素II是一种从海葵（Actinia equina）中分离出的20千道尔顿碱性蛋白。我们这项工作的目的是在两个模型系统中研究海葵毒素II细胞毒性作用的主要分子基础：单个牛催乳细胞和平面脂质双层。先前的研究表明，海葵毒素II会使细胞形态发生快速变化，这种变化依赖于细胞外钙。也有报道称，添加海葵毒素II会增加膜电导，这表明海葵毒素II的细胞毒性作用涉及膜对Ca2+通透性的增加。胞质Ca2+活性的广泛变化被认为会引发细胞生理和形态的不可逆变化。在本文中，我们利用fura-2视频成像设备监测发现，海葵毒素II在牛催乳细胞中引起的形态变化与胞质Ca2+活性的快速升高有关。此外，将海葵毒素II掺入平面脂质双层会产生Ca2+可渗透离子通道。这表明海葵毒素II的细胞毒性作用方式涉及在细胞膜中形成阳离子（Ca2+）可渗透通道。
