CYTOSOLIC MODULATION OF PLASMA MEMBRANE ION TRANSPORT

质膜离子运输的细胞质调节

• 批准号: 3236475
• 负责人: MARK A MILANICK
• 金额: $ 7.8万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-08-01 至 1992-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3236475
• 关键词: adenosine diphosphate; adenosine triphosphate; adenosinetriphosphatase; calcium metabolism; calcium transporting ATPase; cell differentiation; cell membrane; chemical structure function; conformation; cytoplasm; erythrocytes; heart failure; human tissue; hypertension; ion transport; membrane potentials; membrane structure; muscle contraction; muscular dystrophy; myocardium; nucleotides; phosphates; potassium; renal failure; sickle cell anemia; smooth muscle; sodium; striated muscles

The long-term objectives of this research are to elucidate some of the mechanisms of ion transport, to determine how changes of the cytosolic mileau modulate ion transport, and to determine how changes of the cellular environment alter transport rate. The focus of this project is the calmodulin activated Ca pump of red cells, which Is a model for plasma membrane Ca pumps in other cells. Recent evidence indicates that the Ca pump mediates Ca/ll exchange and also Ca transport without H movement. Current models of the Ca pump, while including roles for ATP, ADP, phosphate, and Ca, do not explicitly consider protons. The specific aims of this grant are to examine the effects of extracellular protons and ATP on the red cell Ca pump. Some of the questions to be examined are: l. Are protons important for resetting the pump mechanism after the Ca half cycle? 2. Must Ho bind before ATP can bind to accelerate the return of the transport sites before the next pump cycle can occur? 3. When protons are not transported, what is transported instead? The experimental protocol is to examine the effect of ATP and H on several partial reactions of the Ca pump, including Ca/Ca exchange, pump, including Ca/Ca exchange reversal and phosphointermediate decomposition. One of the goals of a kinetic study is to determine which conformational changes are rate limiting. Regulation of the rate of these conformational changes by alterations in the membrane environment would modulate pump activity. In the red cell it is possible to determine the separate effects of intracellular protons, calcium ions, nucleotide concentrations, and extracellular protons and calcium ions. This is important since, e.g., Cai and Ho are substrates but Cao and Hi are products of the forward pump cycle. A transient rise in Ca is important for signalling in such processes as cardiac, skeletal, and smooth muscle contraction, cell differentiation and cell poliferation. The Ca pump restores Ca to basal levels and therefore assists in terminating the signal. Defects in Ca pump activity would lead to an increase in Ca with subsequent increases in Na and K. These changes would alter key cytoplasmic functions. Such ionic alterations have been implicated in several disease states including renal and cardiac failure, hypertension, and muscular dystrophy. Alterations of the red cell Ca pump have been reported in sickle cell disease.

这项研究的长期目标是阐明一些 离子传输的机制，以确定如何改变 胞质微米数调节离子传输，并确定 细胞环境的变化如何改变传输速率。这个 本课题的研究重点是RED钙调素激活的钙泵 细胞，这是另一种细胞质膜钙泵的模型 细胞。最近的证据表明，钙泵介导了钙/钙离子。 交换和钙的运输也没有氢移动。当前型号 钙泵的作用，同时包括ATP、ADP、磷酸盐和 CA，不要显式地考虑质子。 这笔赠款的具体目的是审查 胞外质子和三磷酸腺苷对红细胞钙泵的影响。其中一些 要考查的问题包括： L。质子对重新启动泵机构重要吗？ 钙半循环？2.必须先结合HO，然后才能与ATP结合 在下一次抽水前加快运输地点的返回 循环可以发生吗？3.当质子没有被传输时，什么 而不是被运输？ 实验方案是检测ATP和H对血管紧张素转换酶的影响。 钙泵的几个部分反应，包括钙/钙交换， 泵，包括钙/钙交换反转和磷中间体 腐烂。动力学研究的目标之一是确定 哪些构象变化是速率限制的。对 这些构象因膜的改变而改变的速率 环境会调节泵的活动。在红血球中是 有可能确定细胞内的分离效应 质子、钙离子、核苷酸浓度和细胞外 质子和钙离子。这一点很重要，因为，例如，蔡和 Ho是底物，而CaO和Hi是前向泵的产物 周而复始。钙的短暂升高对这种情况下的信号转导很重要 如心肌、骨骼肌和平滑肌收缩、细胞 分化和细胞分裂。钙泵将钙恢复到 基础水平，因此有助于终止信号。 钙泵活性的缺陷会导致钙离子的增加 随后钠和钾的增加这些变化将改变关键 细胞质功能。这样的离子变化被牵连到 在包括肾功能衰竭和心力衰竭在内的几种疾病状态下， 高血压和肌肉营养不良。红细胞的变化 钙泵在镰状细胞病中的作用已有报道。