Molecular Mechanism of Photoreceptor G Protein Signaling

光感受器G蛋白信号转导的分子机制

• 批准号: 8895941
• 负责人: Nikolai O Artemyev
• 金额: $ 37万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8895941
• 关键词: Address; Area; Binding; Caenorhabditis elegans; Cells; Cilia; Complex; Defect; Diffusion; Dissociation; Enzymes; Exposure to; G-substrate; GTP-Binding Proteins; Genes; Goals; Guanosine Triphosphate Phosphohydrolases; Health; Heterotrimeric GTP-Binding Proteins; Human; Knockout Mice; Laboratories; Light; Lipids; Mediating; Membrane; Membrane Proteins; Modeling; Molecular; Molecular Structure; Orthologous Gene; Output; Peripheral; Photoreceptors; Phototransduction; Presynaptic Terminals; Property; Protein Isoforms; Protein Subunits; Proteins; Regulation; Research; Resolution; Retina; Retinal Diseases; Rhodopsin; Rod Outer Segments; Roentgen Rays; Role; Signal Transduction; Site; Site-Directed Mutagenesis; Solutions; Structure; Synapses; Testing; Transducin; Transgenic Organisms; Vertebrate Photoreceptors; Vision Disorders; X-Ray Crystallography; base; insight; mutant; novel; phosphodiesterase 6; photoreceptor degeneration; programs; protein complex; protein protein interaction; protein transport; release factor; response; retinal rods; ribbon synapse; trafficking; voltage

DESCRIPTION (provided by applicant): The long-term goal of this research program is to elucidate the molecular mechanisms of transducin (Gt) signaling in rods and cones. A remarkable level of understanding has been achieved in the field on the mechanisms of transducin in the phototransduction cascade. The current focus of our research is on the mechanisms of transducin trafficking and transducin-dependent modulation of photoreceptor responses beyond phototransduction. Very little is known about transport of transducin from the inner segment (IS) to the outer segment (OS). Uncoordinated 119 protein (UNC119) has emerged as a major factor facilitating the IS->OS transport of transducin-� (G�t). We propose to investigate the structure and properties of the trafficking complex between G�t and UNC119 by Small Angle X-ray Scattering (SAXS) and X- ray crystallography. Based on the preliminary SAXS analysis, we hypothesize that a novel interface between UNC119 and G�t is essential to the UNC119-induced dissociation of Gt subunits and protein solubilization from the membrane. The interface and the proposed model of Gt solubilization by UNC119 will be probed with mutational analysis. Solubilization of Gt from IS membranes with the formation of the G�t-UNC119 complex is the initial step in the IS->OS transport of G�t, which terminates with the cargo release into the OS. A small ARF-like 3 GTPase, ARL3, will be investigated as a putative release factor in G�t trafficking. We hypothesize that G�t is released from the complex with UNC119 by a mechanism involving ARL3-induced conformational changes both within and outside the acyl-binding cavity of UNC119 and will test this mechanism. Defects in protein transport are a common cause of photoreceptor degeneration. Elucidation of molecular details of transducin trafficking will significantly contribute to the understanding of transport of peripheral membrane proteins in photoreceptors and will have important implications for retinal diseases. Finally, we will investigate a novel concept on the role of light-dispersed transducin in modulation of the synaptic output of rods. We hypothesize that G�t regulates rod-to-rod bipolar cell signaling by altering UNC119 interactions with major synaptic players, CaBP4 and RIBEYE, and/or via direct effects on the voltage-gated Ca2+ channels and synaptic machinery. The proposed analysis of the synaptic modulation by transducin may profoundly impact the established paradigm on transducin signaling in photoreceptors.

描述（由适用提供）：该研究计划的长期目标是阐明杆和锥体中透明蛋白（GT）信号的分子机制。在光转导级联中跨描绘的机理方面，已经在现场达到了显着的理解。我们研究的当前重点是跨传输反应的跨多霉素运输和跨核素依赖性调节的机制。关于转杜蛋白从内部段（IS）转移到外部段（OS）的传输知之甚少。不协调的119蛋白（UNC119）已成为支持跨蛋白 - > OS转运的主要因素（G t）。我们建议通过小角度X射线散射（SAXS）和X射线晶体学研究G t和UNC119之间运输复合物的结构和特性。基于初步SAXS分析，我们假设UNC119和G≥T之间的新界面对于UNC119诱导的GT亚基解离和从膜上的蛋白质溶液解离至关重要。 UNC119将通过突变分析探测界面和拟议的GT解决方案模型。 GT从IS膜的溶解度随着G≥T-UNC119复合物的形成是G≥T的IS-> OS传输的第一步，G≥T的第一步是随着货物释放到OS中的终止。小型ARF样3GTPase ARL3将被研究为G≥T运输中的推定释放因素。我们假设通过涉及ARL3诱导的构象变化的机制从复合物中释放出GI≥T，并将测试该机制。蛋白质转运的缺陷是感光变性的常见原因。阐明转霉素运输的分子细节将显着有助于理解光感受器中周围膜蛋白的运输，并将对残余疾病具有重要意义。最后，我们将研究一个关于光分散跨多霉素在中的作用的新颖概念 杆的合成输出的调节。我们假设G调节杆到杆杆双极细胞信号传导，通过改变UNC119与主要合成播放器，CABP4和Ribeye的相互作用，以及/或通过直接影响电压门控Ca2+通道和合成机械。跨多霉素对合成调节的拟议分析可能会深刻影响已建立的范例对感光体中的透明蛋白信号传导。