Mechanisms of Sec61-Mediated Polytopic Protein Integration into the ER

描述(由申请人提供)：拟议研究的长期目标是确定确保多通道膜蛋白结构成熟所采用的精确机制步骤，因为它们由核糖体合成并整合到脂质双层中。囊性纤维化与疾病的相关性尤其明显，囊性纤维化是由多位蛋白CFTR突变引起的，导致其错误折叠，从而过早降解。疾病治疗的智能设计最终取决于我们识别与致病突变蛋白一起出错的生物合成事件的能力。使用模型多聚蛋白水通道蛋白4(AQP4)，目前的建议确定跨膜片段从内质网Sec61转位体孔进入脂双层的方式，这是多聚蛋白生物发生的一个基本阶段。此外，在AQP4生物发生的不同阶段，转运子的功能组织将使用生化方法来定义，即通过确定确定阶段的核糖体-转运子复合体的稳定性和组成。因此，这些研究将提供有价值的信息，说明转运子如何循序渐进地组装功能性多聚体蛋白。公共卫生相关性创建疾病治疗方法的一个步骤是调查相关蛋白质突变是如何导致蛋白质功能障碍的。囊性纤维化是由一种膜结合蛋白的突变引起的，这种突变阻止了其结构成熟成为一种功能蛋白。这项研究阐明了膜蛋白获得完全结构成熟的机制，从而为检测膜结合蛋白中与疾病相关的突变提供了一个框架。

DESCRIPTION (provided by applicant): The long term goal of the proposed research is to define the precise mechanistic steps employed to ensure the structural maturation of multi-pass membrane proteins as they are synthesized by the ribosome and are integrated into the lipid bilayer. Relevance to disease is especially apparent in cystic fibrosis, which is caused by mutations in the polytopic protein CFTR, leading to its misfolding and, therefore, premature degradation. Intelligent design of disease treatment ultimately relies upon our ability to identify the biosynthetic event gone awry with disease-causing mutant proteins. Using a model polytopic protein, aquaporin 4 (AQP4), the current proposal determines the manner in which transmembrane segments move from the endoplasmic reticulum Sec61 translocon pore into the lipid bilayer, a fundamental phase during the biogenesis of polytopic proteins. Additionally, the functional organization of the translocon during distinct stages of AQP4 biogenesis will be defined using biochemical measures, namely by determining ribosome-translocon complex stability and composition at defined stages. These studies will, thereby, provide valuable information as to how the translocon proceeds step-wise to assemble functional polytopic proteins. PUBLIC HEALTH RELEVANCE One step in the creation of disease treatment is the investigation of how relevant protein mutations lead to the protein's malfunction. Cystic fibrosis is caused by mutations in a membrane bound protein that prevents its structural maturation into a functional protein. This research elucidates mechanisms by which membrane proteins acquire full structural maturation, thereby, providing a framework to examine disease-related mutations in membrane bound proteins.