INFLUENCE OF PROTEIN/LIPID INTERACTIONS ON SIGNAL TRANSD

蛋白质/脂质相互作用对信号传输的影响

• 批准号: 6097564
• 负责人: Burton J Litman
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6097564
• 关键词: G protein; biological signal transduction; ethanol; fluorescence spectrometry; intermolecular interaction; lipid bilayer membrane; lipid structure; membrane structure; phospholipids; physical chemical interaction; receptor coupling; rhodopsin; rod cell; time resolved data; unsaturated fatty acids

G protein-coupled receptors are ubiquitous components of signal transduction systems. This project is designed to assess the role of polyunsaturated phospholipids in modulating G protein- coupled signal transduction and to elucidate of the mechanism of action of ethanol in these systems. The visual transduction pathway in the rod photoreceptor, a prototypical G protein- coupled system, is being used as a model system. The effect lipid composition on: the kinetics and extent of formation of metarhodopsin II (MII), the G protein activating form of rhodopsin; MII/G protein complex formation; the rate of G protein activation; cGMP phosphodiesterase (PDE) activation; and the GTPase activity of the G protein are being studied. Along with the functional measures in the transduction pathway, acyl chain packing properties of the phospholipid bilayer are being determined by use of time-resolved fluorescence spectroscopy. The isolation and reconstitution of rhodopsin into bilayers of defined lipid composition allows an evaluation of the role of phospholipid acyl chain composition. In the current studies, rhodopsin, G protein, and PDE were reconstituted into phospholipid bilayers composed of 16:0, 18:1 PC or 16:0, 22:6 PC and compared to native disk membrane to which the G protein and PDE were reassociated. At low stimulus levels, twice as much activated rhodopsin was required to obtain equal levels of the light stimulated PDE activity bilayers composed of 16:0, 18:1 PC relative to those composed of 16:0, 22:6 PC. These results demonstrate that the enhanced formation of activated rhodopsin observed in polyunsaturated phospholipids is propagated down the transduction pathway, resulting in higher activity levels in the effector enzyme, PDE. Many of the neurotransmitter receptors are members of the superfamily of G protein-coupled receptors. Thus reductions of polyunsaturated acyl chains in the phospholipids in retinal and neuronal tissue can be expected to result in below optimal receptor function. Our observations in the visual pathway indicate that some part of the observed cognitive and visual deficits in omega-3 deficient animals arises from impaired signaling systems, resulting from the loss of 22:6n3 chains in membrane phospholipids.

G蛋白偶联受体普遍存在 信号转导系统的组成部分。该项目乃设计 评估多不饱和磷脂在调节G 蛋白偶联信号转导，并阐明 乙醇在这些系统中的作用机制。视觉 在视杆细胞中，一种典型的G 蛋白质偶联系统，被用作模型系统。的 影响脂质组成：动力学和程度的形成 后视紫红质II（MII），视紫红质的G蛋白活化形式; MII/G蛋白复合物的形成; G蛋白活化率; cGMP磷酸二酯酶（PDE）激活;以及 G蛋白的活性正在研究中。沿着 转导途径中的功能措施，酰基链包装 磷脂双层的性质是通过使用 时间分辨荧光光谱仪分离和 将视紫红质重构为确定的脂质双层 该组合物允许评价磷脂酰基的作用， 链组成在目前的研究中，视紫红质，G蛋白， 将PDE重构成由以下组成的磷脂双层： 16：0、18：1 PC或16：0、22：6 PC以及与本机磁盘的比较 G蛋白和PDE重新结合的膜。在 低刺激水平，激活视紫红质的两倍， 获得相同水平的光刺激PDE活性所需的 由16：0、18：1 PC组成的双层相对于由 16：0，22：6 PC。这些结果表明，增强 在多不饱和脂肪酸中观察到的活化视紫红质的形成 磷脂沿着转导途径传播， 导致效应酶PDE的活性水平更高。 许多神经递质受体是 G蛋白偶联受体超家族。因此， 在视网膜中的磷脂中的多不饱和酰基链， 神经元组织可预期导致低于最佳受体 功能我们对视觉通路的观察表明， 在omega-3中观察到的认知和视觉缺陷的一部分 缺陷动物是由于信号系统受损， 从膜磷脂中22：6 N3链的丢失。