PROTEIN FOOTPRINTING, APOE, AND ALZHEIMERS DISEASE

这个子项目是利用资源的许多研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 载脂蛋白E（ApoE）在人类中有三种常见的变体，在299个残基的蛋白质中有两个残基不同。 变体ApoE 2在残基112和158处具有半胱氨酸; ApoE 3在112处具有半胱氨酸并且在158处具有精氨酸;并且ApoE 4在两个残基处均具有精氨酸。 由于完整蛋白质的寡聚特性，没有确定任何变体的高分辨率结构。 ApoE 23-164的第一个X-射线晶体结构显示N-末端结构域的四螺旋束结构。 尚未确定分离的C-末端结构域的高分辨率结构，认为该结构域是寡聚相互作用的主要区域。 ApoE 4携带阿尔茨海默病（AD）的任何遗传因素的风险最高。 有证据表明ApoE 4相关AD风险的几种机制，尽管没有达成共识。 值得注意的是，ApoE 4比其他常见的ApoE变体更倾向于形成VLDL脂蛋白，这归因于ApoE 4中N末端：C末端结构域相互作用通过R61和E255之间可能的盐桥增强的构象。 有一个显着的需要，无脂质的ApoE结构的基本理解，以帮助解开突变C158 R的生理后果。 抑制ApoE结构表征的中心问题是寡聚化。 我们获得了ApoE 3的两种突变体，单体浓度为20 mg/mL，具有与ApoE 3相似的脂质结合和LDL受体结合特性。 我们打算研究寡聚化作为一个长期项目的起点，以了解ApoE和Abeta多肽的相互作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Apolipoprotein E (ApoE) has three common variants among humans, differing at two residues in the 299-residue protein. Variant ApoE2 has cysteines at residues 112 and 158; ApoE3 has a cysteine at 112 and an arginine at 158; and ApoE4 has arginines at both residues. No high resolution structure of any variant has been determined, owing to the oligomeric properties of the full protein. The first X-ray crystal structure of ApoE 23-164 revealed a four helix bundle structure of the N-terminal domain. No high resolution structure of the isolated C-terminal domain has been determined, and it is thought that this domain is the primary region of oligomeric interaction. ApoE4 carries the highest risk of any genetic factor for Alzheimer's disease (AD). There is evidence for several mechanisms of ApoE4-associated AD risk, though there is no consensus. Significantly, ApoE4 has a higher preference of forming VLDL lipoproteins than does the other common ApoE variants, and this has been attributed to a conformation involving an N-terminal:C-terminal domain interaction enhanced in ApoE4 by a possible salt bridge between R61 and E255. There is a significant need for a fundamental understanding of the lipid-free ApoE structure, to help unravel the physiological consequence of mutation C158R. The central problem inhibiting the structural characterization of ApoE is oligomerization. We have access to two mutants of ApoE3, monomeric to 20 mg/mL, and possessing similar lipid-binding and LDL receptor-binding properties of ApoE3. We intend to study the oligomerization as a starting point in a long-term project to understand the interactions of ApoE and the Abeta polypeptides.