The Roles of Sodium Pump Beta Subunits in Mammalian Cells

钠泵负责调节和控制细胞、器官中的液体和电解质平衡。 在整个生物体中。它是一种完整的膜蛋白，它利用高达40%的能量 细胞利用细胞水解能逆势主动转运Na、K离子 三磷酸腺苷。该泵由两个主要亚基组成，a亚基，催化亚基，约1000个氨基。 酸和一个约300个氨基酸残基的p亚基，它是高度糖基化的。钠泵，或 Na，K-ATPase，是盐分和液体调节所必需的，仅存在于基底外侧膜上 肾脏和肠道的极化上皮细胞。计划中的实验将集中在细胞上 钠泵的生理作用，重点是p亚单位在哺乳动物细胞中的多种作用。 我们之前的工作导致了一个假说，即p亚基如何促进钠泵p的释放 来自内质网的复合体，使其能够输送到质膜。我们计划测试 在拟议的研究中提出了这一假设。我们还将研究Na泵p亚单位在 在上皮细胞中建立和维持细胞间的接触。我们已经发现了这样的情况 钠泵的独家底侧输送可以被覆盖，它被输送到根尖 浮出水面。我们计划利用这些方案来了解极化膜传递是如何控制的。 在这些实验中，我们还将探索p亚单位糖基化的生理作用，即 目前尚不清楚。我们已经开发了一种调控表达系统来提高p的水平 哺乳动物细胞中的亚基及其基于RNA的还原方法。我们将从以下方面结合战略 分子生物学、细胞生理学、生物化学和共聚焦显微镜，以追求我们的科学目标。这个 钠泵的p亚基在细胞中的作用还不是很清楚。钠泵是主要的 膜蛋白参与液体和电解质平衡，是心脏糖苷的主要靶点。 例如洋地黄，最广泛使用的治疗心功能不全的疗法。钠泵的失调是 还与几种疾病状态有关，包括高血压和偏头痛。报告中提出的工作 目前的应用将提供关于这种重要蛋白质如何在 细胞。

The sodium pump is responsible for the regulation and control of fluid and electrolyte balance in cells, organs and in the entire organism. It is a integral membrane protein that utilizes as much as 40% of the energy of cells to actively transport Na and K ions against their gradients utilizing the energy of hydrolysis of cellular ATP. The pump is composed of two main subunits, the a subunit, the catalytic subunit of about 1000 amino- acids and a p subunit of about 300 amino-acid residues which is heavily glycosylated. The sodium pump, or Na,K-ATPase, is essential for salt and fluid regulation and is found exclusively in the basolateral membrane of polarized epithelial cells of the kidney and intestines. The planned experiments will focus on the cell physiological roles of the sodium pump, focusing on the multiple roles of the p subunit in mammalian cells. Our previous work has led to a hypothesis of how the p subunit facilitates release of the Na pump ¿p complex from the endoplasmic reticulum and enables its delivery to the plasma membrane. We plan to test this hypothesis in the proposed studies. We will also examine the role played by the Na pump p subunit in establishing and maintaining cell-cell contacts in epithelial cells. We have discovered conditions where the exclusive basolateral delivery of the sodium pump can be over-ridden and it is delivered to the apical surface. We plan to utilize these protocols to understand how the polarized membrane delivery is controlled. Throughout these experiments we will also probe the physiological role of p subunit glycosylation, which is currently unknown. We have developed a regulated expression system for increasing the levels of the p subunit in mammalian cells and RNA-based methods for its reduction. We will combine strategies from molecular biology, cell physiology, biochemistry and confocal microscopy to pursue our scientific goals. The cellular roles of the p subunit of the sodium pump are not well understood. The sodium pump is the primary membrane protein involved in fluid and electrolyte balance and is the major target of cardiac glycosides, such as digitalis, the most widely used therapy for cardiac insufficiency. Disregulation of the sodium pump is also associated with several disease states, including hypertension and migraines. The work proposed in the current application will provide new information about how this important protein carries out its functions in cells.