STRUCTURE AND FUNCTION OF THE TOK1 POTASSIUM CHANNEL

TOK 1是新的k+通道家族的第一个成员[1]。 频道， 我们从芽殖酵母酿酒酵母中克隆出来的， 新颖的特征。 首先，它在结构上是不同的。 相比 先前鉴定的K=通道α-亚基，其仅具有一个孔- TOK 1有两个P结构域。 第二，TOK 1是第一个 K+选择性通道的功能类型，一个“外向整流器”。 像 内向整流超家族通道，TOK 1“激活”耦合到 钾的平衡电位（EK），但TOK 1通过K+电流在 外向方向，一个以前未描述的通道表型。 我们的整体 本工作的目标是详细说明TOK 1通道的基本属性， 在可能的情况下，阐明其结构基础。 我们的6个具体目标 未来5年的工作是：（1）详细说明TOK 1的基本单通道特性 （2）探讨TOK 1的分子机制 （3）评价2个P域在神经网络中的功能 完整的通道和当每个P结构域分别表达时;（4） 研究通道的膜拓扑结构，重点是相对的 （5）克隆通道的同源物， 高等生物;（6）应用酵母分子遗传学的工具， TOK 1钾通道结构与功能研究 初步 研究结果提出，以支持这些目标的可行性 使用表达的TOK 1通道的宏观和单通道记录 非洲爪蟾卵母细胞和标准分子遗传工具。

TOK1 is the first member of a new family of k+ channels [1]. The channel, which we cloned from the budding yeast Saccharomyces cerevisiae, has two novel features. First, it is structurally distinct. In contrast to previously identified K= channel alpha-subunits which bear only one pore- forming P domain, TOK1 has two. Second, TOK1 is the first example of a new functional type of K+-selective channel, an "outward rectifier'. Like inward rectifier superfamily channels, TOK1 'activation' is coupled to the equilibrium potential for potassium (EK), but TOK1 passes K+ current in the outward direction, a previously undescribed channel phenotype. Our overall goal in this work is to detail the basic attributes of TOK1 channels and where possible, elucidate their structural basis,. Our 6 specific aims for the next 5 years are: (1) to detail basic single channel properties of TOK1 channels; (2) to investigate the molecular mechanism underlying TOK1 outward rectification; (3) to evaluate function of the 2 P domains in the intact channel and when each of the P domains is expressed separately; (4) to study the membrane topology of the channel with emphasis on the relative arrangement of its 2 P domains; (5) to clone homologues of the channel from higher organism; and, (6) to apply the tools of yeast molecular genetics to study of TOK1 potassium channel structure and function. Preliminary findings are presented to support the feasibility of each of these aims using macroscopic and single channel recording of TOK1 channels expressed in Xenopus laevis oocytes and standard molecular genetic tools.