REGULATION OF PHOSPHOLIPID SYNTHESIS BY CTP

在酿酒酵母中，CTP，CTP合成酶反应 产品，是磷脂的前体， CDP-甘油二酯和Kennedy（CDP-胆碱）途径以及所有 膜磷脂 在本次赠款期间进行的研究 期间显示CTP合成酶活性在 用于合成的途径的利用 卵磷脂 CTP合成酶进行了纯化，表征， 显示通过蛋白激酶A的磷酸化激活， 蛋白激酶C和抑制CTP。 在这个竞争激烈的延续中 我们提出了分子遗传学和生物化学研究的资助申请 这有望提供深入了解CTP的监管 通过磷酸化和CTP产物抑制测定合成酶活性， 这一调节的生理相关性， 磷脂合成 他们建议检验这样一种假设， 通过磷酸化调节CTP合成酶活性涉及 酶的核苷酸依赖性四聚化。 CTP合成酶 突变体将被分离，其具有改变的蛋白激酶A和蛋白质 激酶C磷酸化位点。 这些突变体将用于 生理和生物化学研究，以检查 磷酸化对CTP合成酶活性的调节。的 磷脂合成的这种调节作用将被提出， 分离CTP中建议CTP结合位点缺陷的突变体 合成酶 这些突变体将用于生理和 生物化学研究，以检查CTP合成酶的调节 CTP产物抑制活性。 该条例对 将检查磷脂合成。结果从拟议的 研究应与高等真核生物有关， 对其他调查人员的工作很感兴趣，并补充他们的工作， 磷脂代谢领域。 这项工作也应该是相关的 大分子合成的其他方面， 作为先驱。

In the yeast Saccharomyces cerevisiae, CTP, the CTP synthetase reaction product, is a precursor of phospholipids that are synthesized by the CDP-diacylglycerol and Kennedy (CDP-choline) pathways as well as all membrane phospholipids. Studies performed during the current grant period showed that CTP synthetase activity plays a regulatory role in the utilization of the pathways used for the synthesis of phosphatidylcholine. CTP synthetase was purified, characterized, and shown to be activated by phosphorylation via protein kinase A and protein kinase C and inhibited by CTP. In this competitive continuation grant application we propose molecular genetic and biochemical studies that are expected to provide insight into the regulation of CTP synthetase activity by phosphorylation and by CTP product inhibition and into the physiological relevance of this regulation with respect to phospholipid synthesis. They propose to examine the hypothesis that the regulation of CTP synthetase activity by phosphorylation involves the nucleotide-dependent tetramerization of the enzyme. CTP synthetase mutants will be isolated with altered protein kinase A and protein kinase C phosphorylation sites. These mutants will be used for physiological and biochemical studies to examine the effects of phosphorylation on the regulation of CTP synthetase activity. The effects of this regulation of phospholipid synthesis will be propose to isolate mutants that are defective in a proposed CTP binding site in CTP synthetase. These mutants will be used for physiological and biuochemical studies to examine the regulation of CTP synthetase activity by CTP product inhibition. The effect of this regulation on phospholipid synthesis will be examined. The results from the proposed studies should be relevant to higher eukaryotic organisms and be of great interest to, and complement the work of, other investigators in the field of phospholipid metabolism. This work should also be relevant to other aspects of macromolecular synthesis that are dependent on CTP as a precursor.