Regulation of Nuclear Enzymes by Phytochrome

本项目旨在进一步了解光敏色素对豌豆核内酶的结构、功能和调控作用。光敏色素刺激纯化豌豆核苷三磷酸酶（NTPase）的活性，而钙离子是这种反应所必需的。从豌豆核中分离出一种依赖钙调素的47 kD NTPase，其特性表明它是受光敏色素调节的核NTPase。这种NTPase似乎与哺乳动物细胞核中的核纤层蛋白衍生的46 kD NTPase密切相关，其活性被认为对RNA从细胞核输出很重要。将获得植物NTPase的额外序列信息来证实或反驳这种关系。有证据表明，动物细胞核中纤层蛋白的磷酸化在蛋白水解控制其降解中起着关键作用。豌豆NTPase的磷酸化将被表征，其在NTPase活性调控和从层状蛋白样前体产生NTPase中的作用将被研究。这些结果将有助于更好地理解光如何影响核代谢，也可能对光如何调节植物基因表达的模型产生影响。//

The objective of this project is to learn more about the structure, function and regulation of enzymes in pea nuclei that are stimulated by phytochrome. Phytochrome stimulates the activity of nucleoside triphosphatase (NTPase) in purified pea nuclei, and calcium ions are necessary for this response. A calmodulin- dependent 47 kD NTPase has been isolated from pea nuclei and shown to have properties that implicate it as being the nuclear NTPase that is regulated by phytochrome. This NTPase appears to be closely related to a lamin-derived 46 kD NTPase in mammalian nuclei, whose activity is thought to be important for RNA export from nuclei. Additional sequence information on the plant NTPase will be obtained to confirm or disprove this relationship. There is some evidence that the phosphorylation of lamins in animal nuclei plays a critical role in its controlled degradation by proteolysis. The phosphorylation of the pea NTPase will be characterized, and its role both in the regulation of NTPase activity and in the production of NTPase from lamin-like precursors will be examined. The results should contribute to an improved understanding of how light can influence nuclear metabolism, with possible implications also for models of how light regulates plant gene expression.//