MOLECULAR PHYSIOLOGY OF THE SODIUM PUMP

钠泵的分子生理学

• 批准号: 6800581
• 负责人: JACK H KAPLAN
• 金额: $ 30.89万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6800581
• 关键词: Golgi apparatus; active transport; adenosine triphosphate; electrolyte balance; endoplasmic reticulum; enzyme activity; intracellular transport; molecular assembly /self assembly; protein engineering; protein structure function; site directed mutagenesis; sodium potassium exchanging ATPase; tissue /cell culture; transfection

DESCRIPTION (provided by applicant): The objective of the present work is to obtain a more complete understanding of the molecular physiology of the Na pump or Na,K-ATPase. The Na pump couples the active transport of Na and K ions across the plasma membrane of almost all mammalian cells to the catalysis of ATP hydrolysis. The Na pump is responsible for maintaining normal fluid and electrolyte balance and is essential for renal function and energising reabsorbtion and nutrient uptake. During the past several decades we have learned much about how this oligomeric protein carries out its important function. However, little is known about the control and regulation of the processes which enable the subunits to assemble after synthesis and be delivered as a functioning unit to the plasma membrane. In the present work we will employ the baculovirus-infected insect cell system to introduce Na pump subunits into cells which do not normally express them. We will examine the expression of the sheep alpha1 -subunit (a polytopic membrane protein of 1000 amino acids) and sheep Beta1-subunit (a protein of about 300 amino acids and a single membrane crossing) separately and together and using cell fractionation and metabolic labelling strategies investigate the factors which control their assembly in the endoplasmic reticulum and delivery to the plasma membrane via the golgi apparatus. By utilizing a series of mutations in each sub-unit we will investigate the role of molecular determinants which affect delivery to the plasma membrane, its stability in the membrane and its interactions with cytoskeletal elements. The Na pump is an essential transport system and the site of action of digitalis, the most widely used therapy in cardiac insufficiency. Prospects for improved therapies for cardiac function and for improving impaired renal function will be greatly aided when we have a better understanding of the regulation of the activity of the Na pump in cell membranes.

描述（由申请人提供）：本工作的目的是获得对Na泵或Na,K-ATP酶的分子生理学的更完整的理解。 Na 泵将 Na 离子和 K 离子穿过几乎所有哺乳动物细胞质膜的主动运输与 ATP 水解的催化耦合起来。钠泵负责维持正常的液体和电解质平衡，对于肾功能以及促进重吸收和营养吸收至关重要。在过去的几十年里，我们对这种寡聚蛋白如何发挥其重要功能有了很多了解。然而，对于使亚基在合成后组装并作为功能单元递送至质膜的过程的控制和调节知之甚少。在目前的工作中，我们将利用杆状病毒感染的昆虫细胞系统将Na泵亚基引入通常不表达它们的细胞中。我们将使用细胞分级分离和代谢标记分别和一起检查绵羊 α1 亚基（一种含有 1000 个氨基酸的多胞膜蛋白）和绵羊 Beta1 亚基（一种含有约 300 个氨基酸和单个跨膜的蛋白质）的表达策略研究控制它们在内质网中组装并通过高尔基体递送到质膜的因素。通过利用每个亚基中的一系列突变，我们将研究分子决定因素的作用，这些决定因素影响向质膜的递送、其在膜中的稳定性及其与细胞骨架元素的相互作用。钠泵是重要的运输系统，也是洋地黄的作用部位，洋地黄是治疗心功能不全最广泛使用的疗法。当我们更好地了解细胞膜中钠泵活性的调节时，改进心脏功能治疗和改善受损肾功能的前景将得到极大帮助。