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）蛋白具有特征性疏水长度，该长度由其跨膜α螺旋中疏水残基的数量决定。利用模型肽和双层膜的理论和实验研究表明，疏水性错配可以驱动膜蛋白的缔合。然而，疏水性错配驱动TM蛋白自缔合的可能性尚未在活细胞中测试。疏水性错配也可能对G蛋白偶联受体（GPCR）（细胞表面受体的最大家族）的寡聚化很重要。该项目的第一个目标是测试疏水性错配可以作为驱动活细胞中TM蛋白缔合的机制的一般假设。我们将通过研究具有可变疏水长度的工程化单TM蛋白的自缔合来测试这一假设。该项目的第二个目的是验证疏水性错配有助于活细胞质膜中GPCR自缔合的特定假设。我们将使用HEK 293细胞中的<$2-肾上腺素受体（<$2AR）的自缔合作为模型来检验这一假设。如果成功，这些实验将有助于定义活细胞中TM蛋白组织的机制，<$2AR自缔合的结构基础，并可能提供研究活细胞中单体<$2AR功能的工具。 公共卫生相关性：G蛋白偶联受体是处方药的靶点，比任何其他类型的受体都要多。GPCR可以组装成二聚体或更高阶的寡聚体的认识表明，这些复合物可能具有独特的药理学特性，从而大大扩展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自组装的机制和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，这反过来又可能提供所需的工具，以确定自组装的功能影响。

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.