Miller C, Moczydlowski E, Latorre R, Phillips M
Nature. 1985;313(6000):316-8. doi: 10.1038/313316a0.
The recent development of techniques for recording currents through single ionic channels has led to the identification of a K+-specific channel that is activated by cytoplasmic Ca2+. The channel has complex properties, being activated by depolarizing voltages and having a voltage-sensitivity that is modulated by cytoplasmic Ca2+ levels. The conduction behaviour of the channel is also unusual, its high ionic selectivity being displayed simultaneously with a very high unitary conductance. Very little is known about the biochemistry of this channel, largely due to the lack of a suitable ligand for use as a biochemical probe for the channel. We describe here a protein inhibitor of single Ca2+-activated K+ channels of mammalian skeletal muscle. This inhibitor, a minor component of the venom of the Israeli scorpion, Leiurus quinquestriatus, reversibly blocks the large Ca2+-activated K+ channel in a simple biomolecular reaction. We have partially purified the active component, a basic protein of relative molecular mass (Mr) approximately 7,000.
近年来，通过单离子通道记录电流技术的发展，使得一种由细胞质Ca2+激活的K+特异性通道得以鉴定。该通道具有复杂的特性，可被去极化电压激活，且其电压敏感性受细胞质Ca2+水平调节。该通道的传导行为也很不寻常，其高离子选择性与非常高的单位电导同时表现出来。关于该通道的生物化学性质知之甚少，这主要是由于缺乏合适的配体用作该通道的生化探针。我们在此描述一种哺乳动物骨骼肌单Ca2+激活K+通道的蛋白抑制剂。这种抑制剂是以色列蝎子Leiurus quinquestriatus毒液中的一种次要成分，在一个简单的生物分子反应中可逆地阻断大的Ca2+激活K+通道。我们已部分纯化了活性成分，它是一种相对分子质量（Mr）约为7000的碱性蛋白。
