Hydrophobic mismatch and self-association of TM proteins and beta2 adrenoreceptor

描述(由申请人提供)：α-螺旋跨膜(TM)蛋白具有特征的疏水长度，该长度由其跨膜的α螺旋中的疏水残基的数量决定。使用模型多肽和双层的理论和实验研究表明，疏水错配可以驱动膜蛋白的结合。然而，疏水错配驱动TM蛋白自结合的可能性尚未在活细胞中进行测试。疏水失配也可能是G蛋白偶联受体(GPCRs)寡聚化的重要原因，GPCRs是细胞表面最大的受体家族。拟议项目的第一个目标是测试疏水错配可以作为驱动活细胞中TM蛋白关联的机制的一般假设。我们将通过研究具有不同疏水长度的工程化Single-TM蛋白的自关联来检验这一假设。拟议项目的第二个目标是检验疏水失配导致活细胞质膜中GPCRs自结合的具体假设。我们将使用HEK 293细胞中2-肾上腺素受体(2AR)的自关联作为模型来检验这一假设。如果这些实验成功，将有助于确定活细胞中TM蛋白的组织机制，即2AR自结合的结构基础，并可能为研究活细胞中单体2AR的功能提供工具。 与公共健康相关：G蛋白偶联受体是比任何其他类别的受体更多的处方药的靶标。GPCRs可以组装成二聚体或更高阶低聚物的认识表明，这些复合体可能具有独特的药理特性，从而极大地扩大了潜在治疗靶点的数量。为了充分评估这种可能性，有必要了解GPCR自组装的机制以及自组装对功能的影响。拟议研究的目标是确定自组装的机制，这反过来可能提供确定自组装的功能影响所需的工具。

DESCRIPTION (provided by applicant): Alpha-helical transmembrane (TM) proteins possess a characteristic hydrophobic length that is determined by the number of hydrophobic residues in their membrane-spanning alpha helices. Theoretical and experimental studies using model peptides and bilayers suggest that hydrophobic mismatch can drive the association of membrane proteins. However, the possibility that hydrophobic mismatch drives self-association of TM proteins has not been tested in living cells. Hydrophobic mismatch might also be important for oligomerization of G protein-coupled receptors (GPCRs), the largest family of cell surface receptors. The first objective of the proposed project is to test the general hypothesis that hydrophobic mismatch can serve as a mechanism that drives TM protein association in living cells. We will test this hypothesis by studying self-association of engineered single-TM proteins with variable hydrophobic lengths. The second objective of the proposed project is to test the specific hypothesis that hydrophobic mismatch contributes to self-association of GPCRs in the plasma membrane of living cells. We will test this hypothesis using self-association of ¿2-adrenoreceptors (¿2ARs) in HEK 293 cells as a model. If successful these experiments will help to define the mechanisms of TM protein organization in live cells, the structural basis of ¿2AR self-association, and may provide tools to study the function of monomeric ¿2ARs in living cells. PUBLIC HEALTH RELEVANCE: G protein-coupled receptors are the targets of more prescribed drugs than any other class of receptor. The realization that GPCRs can assemble as dimers or higher-order oligomers suggests the possibility that these complexes might have unique pharmacological properties, thus greatly expanding the number of potential therapeutic targets. In order to fully evaluate this possibility it is necessary to understand both the mechanism of GPCR self-assembly and the impact of self-assembly on function. The goal of proposed research is to determine the mechanism of self-assembly, which in turn may provide the tools needed to determine the functional impact of self-assembly.