ACTIVATION OF CTP--PHOSPHOCHOLINE CTIDYLYTRANSFERASE

酶CTP：磷酸胆碱胞苷酰转移酶（CT）是一种关键的酶。 CDP-胆碱途径的成员，用于生物合成 磷脂酰胆碱，真核细胞膜的主要成分 以及信号转导途径重要成分的前体， 如甘油二酯和磷脂酸。 CT是速率限制的 CDP-胆碱途径，因此在细胞内广泛调节。 细胞水平。 CT以可溶性和膜相关的形式存在， form. 在许多细胞中，CT的激活与细胞周期的变化同时发生。 酶从可溶性形式转移到膜结合形式， 形式，而在体外，CT的可溶性形式通过添加 某些脂类的。 拟议的研究将利用重组形式 大鼠肝CT、S. cerevisiae和C. elegans来调查 脂质激活酶的机制。 脂质结合区 S. cerevisiae和C.线虫CT的鉴定及其解决方案 结构将解决旁边的大鼠脂质结合区 利用核磁共振。 突变酶截短为 去除每种形式的CT的脂质结合区域将被分析， 以确定CT的脂质结合区是否 作为抑制成分限制酶的活性， 缺乏激活脂质。 阐明其机制， 脂质激活CT将增强对细胞 调节这种关键酶，它提供了主要成分 哺乳动物细胞膜，细胞中央的区域， 信号转导途径的启动导致细胞生长 或细胞死亡。

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.