Acid-Base and Ammonia Transport in the Collecting Duct

酸碱和氨在收集管中的传输

• 批准号: 8511335
• 负责人: L Lee HAMM
• 金额: --
• 依托单位: SOUTHEAST LOUISIANA VETERANS HEALTH CARE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8511335
• 关键词: Accounting; Acid-Base Equilibrium; Acids; Address; Ammonia; Ammonium; Bacteria; Bicarbonates; Biological Assay; Carbon Dioxide; Cellular Assay; Characteristics; Chronic; Chronic Kidney Failure; Data; Diabetes Mellitus; Diagnosis; Disease; Distal; Duct (organ) structure; Equilibrium; Erythroid; Excretory function; Gases; Glycoproteins; Goals; Health; Homeostasis; Human; Hypertension; In Vitro; Ions; Kidney; Liver; Measurement; Measures; Mediator of activation protein; Membrane Proteins; Microelectrodes; Modeling; Molecular; Mus; Nephrons; Physiological; Prevention; Process; Property; Proteins; Regulation; Renal function; Resolution; Role; Site-Directed Mutagenesis; Skin; Structure; Techniques; Testis; Up-Regulation; Urine; Veterans; Work; Yeasts; base; kidney cortex; novel; pH Homeostasis; protein transport; public health relevance; research study; solute; voltage; voltage clamp

DESCRIPTION (provided by applicant): Renal excretion of NH4+ is critical for acid-base homeostasis, normally accounting for at least two-thirds of daily net acid excretion in the urine. Recent studies have identified new non- erythroid Rh proteins that are related to the NH4+ transporters in non-mammalian species. Normal acid-base balance is essential for health and prevention of progression of chronic kidney disease. The main purpose of this proposal is to determine the functional and structural properties of renal Rh glycoproteins with respect to NH3/NH4+ transport and CO2 transport which is also critical for acid-base homeostasis. Among the properties to be explored are their critical sensitivity to pH; a potential role as transporters of gases and the possibility that they serve dual roles as NH4+ and NH3 transporters. Specifically we will address the following aims: 1) Transport characteristics of Rh glycoproteins: The main hypothesis of this aim is that Rhbg and Rhcg are transporters of NH4+ (and possibly NH3). 2) Structure-function characteristics of Rh glycoproteins: Site-directed mutagenesis of critical residues & functional assays will be conducted to determine why different Rh glycoproteins transport NH3/NH4+ differently. 3) Transport of NH3 and CO2 by Rh glycoproteins: We will determine if Rh proteins transport NH3 or CO2. This property is novel & unique in that very few membrane proteins have been identified as mediators of gas transport. Our studies employ a combination of techniques (pHi studies, voltage clamp experiments, site-directed mutagenesis) that should clearly establish whether Rh proteins act as NH3 or CO2 or NH4+ transporters and the characteristics of this transport. This work relies on in vitro experiments because of the difficulties inherent in characterizing NH3/NH4+ transport. The proposed work is substantial, but our ultimate goals are to understand the physiologic significance and regulation of these processes in the kidney.

描述（由申请人提供）： NH4+的肾脏排泄对于酸碱稳态至关重要，通常是尿液中至少三分之二的每日净酸排泄。最近的研究已经确定了与非哺乳动物物种中NH4+转运蛋白相关的新的非性RH蛋白。正常的酸碱平衡对于健康和预防慢性肾脏疾病进展至关重要。 该提案的主要目的是确定相对于NH3/NH4+转运和CO2转运的肾脏RH糖蛋白的功能和结构特性，这对于酸碱稳态也至关重要。在要探索的属性中，它们对pH值的关键敏感性；作为气体转运蛋白的潜在作用以及它们的可能性 将双重作用作为NH4+和NH3转运蛋白。具体而言，我们将解决以下目的：1）RH糖蛋白的转运特征：该目标的主要假设是RHBG和RHCG是NH4+的转运蛋白（可能是NH3）。 2）RH糖蛋白的结构功能特征：将进行关​​键残基和功能测定的位置定向诱变，以确定为什么不同的RH糖蛋白转运NH3/NH4+不同。 3）RH糖蛋白通过RH糖蛋白运输NH3和CO2：我们将确定RH蛋白是否转运NH3或CO2。该特性是新颖且独特的，因为很少有膜蛋白被确定为气体传输的介体。 我们的研究采用了技术的组合（PHI研究，电压夹实验，定点诱变），这些技术应清楚地确定RH蛋白是否充当NH3或CO2或NH4+转运蛋白以及该运输的特征。这项工作依赖于体外实验，因为表征NH3/NH4+转运的困难。拟议的工作是实质性的，但我们的最终目标是了解肾脏这些过程的生理意义和调节。