EPR STUDIES OF MEMBRANE PROTEINS

阴离子交换蛋白(带3)是人类体内含量丰富的蛋白质 红细胞膜由两个区域组成，它们服务于 不同的功能。整体式膜域便于 碳酸氢盐和氯化物的交换，从而增加二氧化碳 血液的承载能力。细胞质结构域作为一种 包括锚蛋白和条带4.2在内的外周蛋白的结合位点 它们参与形成等离子体之间的物理联系 膜和膜骨架。这些蛋白质之间的相互作用 对于保持独特的双凹形状和 红细胞的粘弹性特性。第三带的遗传缺陷， Ankyrin或带4.2导致细胞形状异常，坚硬或脆弱 细胞，通常是临床上有意义的溶血性贫血。长的- 这些研究的学期目标是确定结构和动态 对其作为组织者的角色至关重要的3个频段的特性 稳定红细胞的蛋白质-蛋白质相互作用中心 薄膜。 据推测，带3主要以二聚体的形式存在 四聚体，这些小的低聚物与膜相互作用 骨骼通过灵活的连杆，和灵活性的 带3的细胞质结构域对于正常的细胞形态和 机械性能。在下一个授权期，电子顺磁 共振光谱、荧光光谱和磷光光谱将被 结合经典的生物化学方法来解决以下问题 具体问题：1)低聚物物种的大小是什么 带3存在于红细胞膜上？2)有多灵活，就 在运动的幅度中，是细胞质区域的一段 带3，它将膜骨架连接到脂质双层，并 这些链接在多大程度上存在于完整的细胞中？3)这些链接是什么 特定的蛋白质-蛋白质相互作用的性质涉及 带3的细胞质结构域及其结合蛋白ankyrin和band 4.2？为了帮助实现这些目标，新的分子探测器， 将开发光谱方法和数据分析方法， 将在生物医学研究领域发挥作用。

The anion exchange protein (band 3) is an abundant protein in the human erythrocyte membrane which is composed of two domains that serve distinct functions. The integral membrane domain facilitates the exchange of bicarbonate and chloride, thereby increasing the CO2 carrying capacity of the blood. The cytoplasmic domain serves as a binding site for peripheral proteins including ankyrin and band 4.2 which are involved in forming a physical link between the plasma membrane and the membrane skeleton. These protein-protein interactions are essential for maintaining the unique biconcave shape and viscoelastic properties of erythrocytes. Genetic defects in band 3, ankyrin, or band 4.2 result in abnormal cell shapes, rigid or fragile cells, and often, clinically significant hemolytic anemias. The long- term goals of these studies are to determine the structural and dynamic properties of band 3 that are essential for its role as an organizing center for protein-protein interactions which stabilize the erythrocyte membrane. It is hypothesized that band 3 is present primarily as dimers and tetramers, that these small oligomers interact with the membrane skeleton via a flexible linkage, and that the flexibility of the cytoplasmic domain of band 3 is necessary for normal cell shape and mechanical properties. In the next grant period, electron paramagnetic resonance, fluorescence, and phosphorescence spectroscopies will be combined with classical biochemical methods to address the following specific questions: 1) What are the sizes of the oligomeric species of band 3 present in the erythrocyte membrane? 2) How flexible, in terms of the amplitude of motion, is the segment of the cytoplasmic domain of band 3 which links the membrane skeleton to the lipid bilayer, and to what extent do these links exist in the intact cell? 3) What are the properties of specific protein-protein interactions involving the cytoplasmic domain of band 3 and the binding proteins ankyrin and band 4.2? To help accomplish these goals, new molecular probes, spectroscopic methods, and data analysis methods will be developed which will be of utility in the biomedical research community.