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。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 载脂蛋白E(ApoE)在人类中有三个常见的变体，不同的是299个残基蛋白中的两个残基。变异体APOE2在第112和158位有半胱氨酸；ApoE3在第112位有半胱氨酸，在158位有精氨酸；ApoE4在这两个残基都有精氨酸。由于完整蛋白质的寡聚体性质，还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-末端结构域为四螺旋束结构。分离的C-末端结构域的高分辨率结构尚未确定，该结构域被认为是低聚物相互作用的主要区域。 在阿尔茨海默病(AD)的任何遗传因素中，ApoE4的风险最高。有证据表明ApoE4相关的AD风险有几种机制，尽管还没有达成共识。值得注意的是，ApoE4比其他常见的ApoE变异体更倾向于形成VLDL脂蛋白，这被归因于一种涉及N末端的构象：通过R61和E255之间可能的盐桥，ApoE4中的C末端结构域相互作用增强。有必要对无脂ApoE结构有一个基本的了解，以帮助揭开C158R突变的生理后果。 阻碍载脂蛋白E结构表征的中心问题是寡聚。我们获得了ApoE3的两个突变体，单体浓度为20 mg/mL，具有与ApoE3相似的脂结合和低密度脂蛋白受体结合特性。我们打算研究寡聚作为一个长期项目的起点，以了解载脂蛋白E和载脂蛋白β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.