Coupling Between ATP Hydrolysis and H+ Transport by ATPases in the Plasma Membrane and Tonoplast of Plant Cells

植物细胞质膜和液泡膜中 ATP 酶的 ATP 水解和 H 转运之间的耦合

• 批准号: 9220260
• 负责人: Roger Spanswick
• 金额: --
• 依托单位: Cornell Univ - State: AWDS MADE PRIOR MAY 2010
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-09-01 至 1996-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9220260&HistoricalAwards=false
• 关键词: Coupling; Between; ATP; Hydrolysis; H+

99220260 Spanswick This research is the continuation of a program designed with the long term objective of understanding transport in plant cells in terms of a chemiosmotic scheme for the transport of ions across plant cell membranes. The specific problem addressed in this proposal is that raised by the observation that the coupling between ATP hydrolysis and proton transport by ATPases from both the plasma membrane and the tonoplast appears to be variable depending, for example, upon the concentration of anions present in the membrane vesicle suspension. Hypotheses involving intrinsic u coupling between transport and ATPase activity ("slip") or electrically driven passive proton fluxes ("leak") will be tested by a variety of methods to account for the apparent discrepancy between anion stimulation of ATPase-mediated proton fluxes and of ATPase activity. %%% A proper distribution of salts between the inside and outside of a cell and the inside and outside of individual cellular compartments is critical for the normal function of all cells. The long term goal of this research is to understand the transport mechanisms for ions such as protons, potassium, and sodium (the components of salts) across the membranes of plant cells to maintain their normal distributions. This requires understanding the properties of the individual ion transport systems. A useful overall hypothesis for the mechanism of ion transport is based on a scheme in which the primary active transport systems are enzymes that transport protons (hydrogen ions) across cell membranes against an electrochemical gradient, using energy from hydrolysis of the energy-rich molecule, ATP. According to this scheme, other ions are transported by way of secondary systems that derive their energy from the electrochemical gradient of protons. (Transport of calcium ions across the plasma membrane is an exception.) The specific goal of this project is to study in some detail the relation between ATP hydro lysis and proton transport across the plant cell outer membrane and the membrane of an intracellular compartment, the tonoplast. The results of this research should provide a fundamental piece of the puzzle that in the long run will result in a complete understanding of how plants maintain their salt balance. ***

99220260 Spanswick本研究是一项计划的延续，该计划旨在了解植物细胞中离子跨植物细胞膜运输的化学渗透方案的长期目标。在这个建议中解决的具体问题是，所提出的观察，ATP水解和质子运输的ATP酶从质膜和液泡膜之间的耦合似乎是可变的，取决于，例如，在膜囊泡悬浮液中存在的阴离子的浓度。将通过多种方法测试涉及运输和ATP酶活性（“滑移”）或电驱动的被动质子通量（“泄漏”）之间的内在u耦合的假设，以解释ATP酶介导的质子通量和ATP酶活性的阴离子刺激之间的明显差异。盐在细胞内外以及单个细胞区室内外之间的适当分布对于所有细胞的正常功能至关重要。这项研究的长期目标是了解质子、钾和钠等离子（盐的组分）穿过植物细胞膜以维持其正常分布的运输机制。这需要了解单个离子传输系统的特性。离子转运机制的一个有用的总体假设是基于一个方案，其中主要的主动转运系统是利用富含能量的分子ATP水解产生的能量逆着电化学梯度将质子（氢离子）转运穿过细胞膜的酶。根据该方案，其他离子通过二级系统传输，该二级系统从质子的电化学梯度获得能量。（钙离子穿过质膜的转运是个例外。）该项目的具体目标是详细研究ATP水解和质子跨植物细胞外膜和细胞内隔室膜（液泡膜）的运输之间的关系。这项研究的结果应该提供了一个基本的拼图，从长远来看，将导致一个完整的理解植物如何保持其盐平衡。***