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）蛋白具有疏水长度的特征，这是由其跨膜α螺旋中疏水残基的数量决定的。利用模型肽和双分子层进行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。疏水错配可能对G蛋白偶联受体（gpcr）的寡聚化也很重要，gpcr是细胞表面受体中最大的家族。该项目的第一个目标是验证疏水错配可以作为驱动TM蛋白在活细胞中结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单tm蛋白的自关联来验证这一假设。该项目的第二个目标是测试疏水错配有助于活细胞质膜中gpcr自结合的特定假设。我们将使用HEK 293细胞中¿2-肾上腺素受体（¿2ARs）的自我结合作为模型来验证这一假设。如果实验成功，将有助于明确TM蛋白在活细胞中的组织机制、¿2AR自结合的结构基础，并可能为研究单体¿2AR在活细胞中的功能提供工具。

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.