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定义用于确保多通道膜蛋白在由核糖体合成并整合到脂质双层中时结构成熟的精确机械步骤。与疾病的相关性在囊性纤维化中尤其明显，囊性纤维化是由多位蛋白CFTR的突变引起的，导致其错误折叠，因此过早降解。疾病治疗的智能设计最终依赖于我们识别致病突变蛋白的生物合成事件出错的能力。使用一个模型的多位蛋白，水通道蛋白4（AQP 4），目前的建议确定的方式，跨膜段从内质网Sec 61 translocon孔进入脂质双层，一个基本阶段在多位蛋白的生物发生。此外，在AQP 4生物发生的不同阶段期间，易位子的功能组织将使用生物化学措施来定义，即通过确定在定义的阶段的核糖体-易位子复合物的稳定性和组成。因此，这些研究将提供有价值的信息，如何进行逐步的易位组装功能的多位蛋白。公共卫生相关性创造疾病治疗方法的一个步骤是研究相关蛋白质突变如何导致蛋白质的功能障碍。囊性纤维化是由膜结合蛋白的突变引起的，该突变阻止其结构成熟为功能蛋白。这项研究阐明了膜蛋白获得完全结构成熟的机制，从而提供了一个框架，以检查疾病相关的突变膜结合蛋白。

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.