ACTIVATION OF CTP--PHOSPHOCHOLINE CTIDYLYTRANSFERASE

CTP：磷酸胆碱胞苷转移酶(CT)是一种关键的 CDP-胆碱途径的成员，用于生物合成 真核细胞膜的主要成分--磷脂酰胆碱 以及信号转导途径的重要组成部分的前身，如 如甘油二酯和磷脂酸。CT是限速的 CDP-胆碱途径因此受到广泛的调控 细胞水平。CT既表现为可溶性的，也表现为膜相关的 形式。在许多细胞中，CT的激活与 酶从可溶性形式向膜相关形式的转移 形式，而在体外，可溶形式的CT被添加激活 某些脂类。拟议的研究将利用重组形式 从大鼠肝脏、酿酒葡萄球菌和秀丽隐杆线虫中提取CT 脂类激活酶的机制。脂类结合区 酿酒葡萄球菌和线虫CT的鉴定及其解决方案 大鼠脂结合区旁边的结构将被解决 利用核磁共振。突变酶被截断为 去除脂质结合区的每一种形式的CT都会进行分析 体外和体内测定CT的脂质结合区 作为一种抑制元件，限制该酶的活性 没有激活的脂类。阐明其致病机制 脂质激活CT将增强对细胞的了解 对这种关键酶的调节，它提供了主要成分 在哺乳动物细胞膜中，位于细胞中央的区域 启动导致任一细胞生长的信号转导通路 或者细胞死亡。

The enzyme CTP:phosphocholine cytidylyltransferase (CT) is a critical member of the CDP-choline pathway, for the biosynthesis of phosphatidylcholine, the major component of eukaryotic cell membranes and a precursor to vital components of signal transduction pathways such as diacylglycerol and phosphatidic acid. CT is rate-limiting for the CDP-choline pathway and therefore is extensively regulated at the cellular level. CT is present as both a soluble and membrane-associated form. In many cells, activation of CT occurs simultaneously with the translocation of the enzyme from a soluble form to membrane-associated form, while in vitro the soluble form of CT is activated by the addition of certain lipids. The proposed research will utilize recombinant forms of CT from rat liver, S. cerevisiae, and C. elegans to investigate the mechanism whereby lipids activate the enzyme. Lipid-binding regions of S. cerevisiae and C. elegans CT will be identified and their solution structures will be solved alongside the rat lipid binding region utilizing Nuclear Magnetic Resonance. Mutant enzymes truncated to remove the lipid binding region of each form of CT will be analyzed both in vitro and in vivo to determine if the lipid binding region of CT serves as an inhibitory element to limit the activity of the enzyme in the absence of activating lipids. Elucidation of the mechanism whereby lipids activate CT will enhance the understanding of the cellular regulation of this pivotal enzyme, which provides the major constituent of mammalian cell membranes, the region of the cell central to the initiation of signal transduction pathways leading to either cell growth or cell death.