Jonas Kim C, Huhtaniemi Ilpo, Hanyaloglu Aylin C
Institute of Reproductive and Developmental Biology, Imperial College London, London, UK; Institute of Medical and Biomedical Education, St George's University of London, London, UK.
Institute of Reproductive and Developmental Biology, Imperial College London, London, UK.
Methods Cell Biol. 2016;132:55-72. doi: 10.1016/bs.mcb.2015.11.005. Epub 2015 Dec 24.
The organization of G protein-coupled receptors (GPCRs) into dimers and higher-order oligomers has provided a potential mechanistic system in defining complex GPCR responses. Despite being studied for nearly 20 years it has, and still is, been an area of controversy. Although technology has developed to quantitatively measure these associations in real time, identify the structural interfaces and even systems to understand the physiological significance of di/oligomerization, key questions remain outstanding including the role of each individual complex from the monomer to the higher-order oligomer, in their native system. Recently, single-molecule microscopy approaches have provided the tools to directly visualize individual GPCRs in dimers and oligomers, though as with any technological development each have their advantages and limitations. This chapter will describe these recent developments in single-molecule fluorescent microscopy, focusing on our recent application of super-resolution imaging of the GPCR for the luteinizing hormone/chorionic gonadotropin to quantify GPCR monomers and formation of protomers in to dimers and distinct oligomeric forms. We present our approach, considerations, strategy, and challenges to visualize this receptor beyond the light diffraction limit via photoactivated localization microscopy with photoactivatable dyes. The addition of super-resolution approaches to the GPCR "nano-tool kit" will pave the way for novel avenues to answer outstanding questions regarding the existence and significance of these complexes to GPCR signaling.
G蛋白偶联受体(GPCRs)形成二聚体和高阶寡聚体,为定义复杂的GPCR反应提供了一个潜在的机制系统。尽管已经研究了近20年,但它一直是,并且仍然是一个有争议的领域。尽管技术已经发展到可以实时定量测量这些相互作用,识别结构界面,甚至发展到能够理解二聚化/寡聚化生理意义的系统,但关键问题仍然悬而未决,包括从单体到高阶寡聚体的每个单独复合物在其天然系统中的作用。最近,单分子显微镜方法提供了直接可视化二聚体和寡聚体中单个GPCR的工具,不过与任何技术发展一样,每种方法都有其优点和局限性。本章将描述单分子荧光显微镜的这些最新进展,重点介绍我们最近将GPCR的超分辨率成像应用于促黄体生成素/绒毛膜促性腺激素,以量化GPCR单体以及原聚体形成二聚体和不同寡聚体形式的情况。我们展示了通过使用光活化染料的光活化定位显微镜,在超出光衍射极限的情况下可视化该受体的方法、注意事项、策略和挑战。将超分辨率方法添加到GPCR“纳米工具包”中将为回答有关这些复合物对GPCR信号传导的存在和意义的悬而未决问题开辟新途径。