ERYTHROCYTE MEMBRANE STRUCTURE

红细胞膜在几乎每一本现代生物化学教材中都被描述为质膜的模型， 因为i)它的膜结构相对简单，ii)它的蛋白质成分或它们的同系物是 几乎存在于人体的每一个细胞中。红细胞膜(RBCM)的结构也与 血液学，因为它的结构缺陷会导致溶血性贫血，血液流动异常，以及 止血。对于RBCM的结构和功能至关重要的是连接脂质双层和 以血影蛋白为基础的膜骨架；即带3-锚蛋白-血影蛋白桥和血糖蛋白C蛋白，^.l- 幽灵蛋白/肌动蛋白桥。这两个桥中的任何一个的缺陷都会导致细胞形态改变和不必要的膜脆性。 这项提案的首要目标是确定这两座大桥的结构和监管特点。具体来说， 我们将完成带3胞质结构域(Cdb3)的晶体结构测定，其中最显著的是 膜上基于幽灵蛋白的骨架的锚定(目标1)。因为CDB3还结合了蛋白质4.1、蛋白质4.2、几个 糖酵解酶、血红蛋白、半红细胞和蛋白质酪氨酸激酶p72syk的特定序列，这种结构 决心应该极大地扩展我们对这个膜组织中心的理解。因为我们的水晶 锚蛋白的带3结合结构域现已可用，其晶体结构也将得到解决。 第二个目标将集中在表征带3-Ankyrin-Spectrin桥的调节。目前的数据表明 这一调节是通过带3的磷酸化或调节四聚体和二聚体平衡来执行的 带3.将详细研究引发上述两种监管变化的效应器。 最终的特定目标(目标3)将评估血糖素C蛋白4.1-血影蛋白/肌动蛋白桥的调节。 初步数据显示，肌醇-L、4，5-三磷酸(IP)、钙调蛋白和2，3-二磷酸甘油都起作用 在这项规定中的突出作用。这些可能性将在纯化的生化系统和现场进行测试。作为一名 这些研究的结果是，对调节红细胞形状和机械性能的因素有了更深入的了解 稳定应该随之而来。

The erythrocyte membrane is depicted in virtually every modern biochemistry text as a model of a plasma membrane, because i) its membrane architecture is comparatively simple, and ii) its protein components or their homologues are present in virtually every cell of the body. The structure of the red blood cell membrane (RBCM) is also of relevance to hematology, because defects in its structure lead to hemolytic anemias, abnormalities in blood flow, and problems in hemostasis. Critical to the structure and function of the RBCM are the two bridges that connect the lipid bilayer to the underlying spectrin-based membrane skeleton; i.e.the band 3-ankyrin-spectrin bridge and the glycophorin C-protein,^.l- spectrin/actin bridge. Defects in either of these bridges lead to altered cell morphology and unwanted membrane fragility. The overriding objective of this proposal is to characterize the structure and regulation of these two bridges. Specifically, we will finish the crystallographic structure determination of the cytoplasmic domain of band 3 (cdb3), the most prominent anchor of the spectrin-based skeleton at the membrane (aim 1). Because cdb3 also binds protein 4.1,protein 4.2,several glycolytic enzymes, hemoglobin, hemichromes, and the protein tyrosine kinase p72syk at defined sequences, this structure determination should greatly expand our understanding of this center of membrane organization. Since crystals of the band 3 binding domain of ankyrin are now available, its crystallographic structure will also be solved. A second aim will focus on characterizing the regulation of the band 3-ankyrin-spectrin bridge. Current data indicate that this regulation is executed either via phosphorylation of band 3 or modulation of the tetramer<->dimer equilibrium of band 3. The effectors that initiate both of the above regulatory changes will be examined in detail. The final specific aim (aim 3) will evaluate the regulation of the glycophorin C-protein 4.1-spectrin/actin bridge. Preliminary data suggest that inositol-l,4,5-trisphosphate (IPs), calmodulin, and 2,3-diphosphoglycerate all play prominent roles in this regulation. These possibilities will be tested in both purified biochemical systems and in situ. As a consequence of these studies, a more thorough understanding of the factors that regulate RBC shape and mechanical stability should ensue.