Genetics and Biochemistry of Ca++-Dependent K+ Channels

原生动物四脲草履虫（Paramecium tetraurelia） 以向后游泳的形式对各种 的刺激。 向后游泳与动作相关 可以记录的跨表面膜的电位 有机体 动作电位涉及四种特定的离子 电压依赖性钙通道，电压- 依赖性钾通道和两个钙依赖性通道， 一种对钾有选择性，另一种对钠有选择性。 本研究的总体目标是了解分子 参与钙依赖性调节的成分 草履虫钾通道 最近的研究使用 一种叫做泛恐怖症患者的行为突变体已经表明， 钙结合蛋白，钙调蛋白，参与了 钙依赖性钾通道的调节。 为了更全面地了解 该通道的调节以及该通道在 草履虫行为的遗传和生化结合 将采取办法。 泛恐怖症患者的生化变化 影响通道的突变体将被更充分地表征， 和钙调素结合蛋白参与通道调节 将被分离并鉴定。 细胞中的离子通道一般由复合物组成 膜蛋白，并作为门控孔的功能， 离子穿过细胞膜的有序运输。 它们的功能， 除了参与草履虫的行为， 神经和肌肉的兴奋以及 许多细胞类型的环境刺激。 分子 到目前为止，离子通道的功能机制还很差， 明白 草履虫提供了一个很好的系统， 离子通道的研究，因为它可以被基因操纵 并且可以获得大量相同的细胞以提供 为生物化学研究提供了充足的材料。 的结果 研究将提供重要的新信息 调节钙依赖性的分子机制 钾离子通道

The protozoan, Paramecium tetraurelia undergoes a behavioral response in the form of backward swimming to a variety of stimuli. Backward swimming is correlated with action potentials that can be recorded across the surface membrane of the organism. The action potential involves four specific ion channels, a voltage-dependent calcium channel, a voltage- dependent potassium channel, and two calcium dependent channels, one that is selective for potassium and the other for sodium. The overall goal of this research is to understand the molecular components involved in the regulation of the calcium-dependent potassium channel from Paramecium. Recent studies using the behavioral mutant called pantophobiac have shown that the calcium-binding protein, calmodulin, is involved in the regulation of the calcium-dependent potassium channel. To understand more fully the molecular mechanism of the regulation of this channel and the role of the channel in the behavior of Paramecium a combined genetic and biochemical approach will be taken. Biochemical changes in pantophobiac mutants that affect the channel will be characterized more fully, and calmodulin-binding proteins involved in channel regulation will be isolated and characterized. Ion channels in cells are generally composed of complexes of membrane proteins, and function as gated pores for the orderly transport of ions across cell membranes. Their function, besides being involved in the behavior of Paramecium, is the basis for excitation in nerve and muscle and for the responses of many cell types to environmental stimuli. The molecular mechanisms by which ion channels function are, as yet, poorly understood. Paramecium provides an excellent system for basic studies of ion channels because it can be genetically manipulated and large numbers ofidentical cells can be obtained to provide sufficient material for biochemical studies. The results of this research will provide important new information about the molecular mechanism of regulation of the calcium-dependent potassium channel.