MEMBRANE BASIS OF VISUAL EXCITATION

描述：这项研究的主要目标是调查 视神经冲动触发的分子基础 脊椎动物的鱼竿。对这些分子机制的了解可以提供一种 关于视觉的最终治疗干预的概念基础 精神错乱。该棒包括超分子组件，其中 视网膜盘膜含有视紫红质，视紫红质是一种完整的膜蛋白， 与组成紧密的特征双层脂质一起 受监管的。视紫红质是视觉中的关键信号转导事件 I向后视紫红质II构象转变。他们将测试 假设在视紫红质的光激发下，视网膜希夫碱 被去质子化，导致盐桥断裂 Glu-113，它被传播到受体的细胞质环。AS 因此，Meta I-Meta II转变对形变很敏感 膜脂双分子层的能量。视网膜色素变性等疾病 (Rp)可能与Meta I-Meta II平衡的扰动有关， 由于视紫红质的突变或双层脂质的改变 环境。将采用两种互补的生物物理方法： 氚(2H)核磁共振谱和表面等离子体共振(SPR) 光谱学。(I)2H核磁共振波谱将研究 启动Meta I-Meta II构象的双分子层形变能 视紫红质的改变，由于面积或曲率受挫 膜自由能。(Ii)视紫红质的视网膜生色团 将进行2H标记的和2H核磁共振研究，以阐明 暗状态下视网膜生色团的构象和取向。 然后，他们将研究光激发时发生的变化， 导致跨膜螺旋的运动和形成 已激活Meta II状态。(Iii)负载型视紫红质的SPR谱 平面双层将被用来确定 螺旋影响受体的细胞质环，产生 暴露G蛋白(转导蛋白)的识别位点。其他内容 SPR研究将调查结合常数和信号状态 参与视觉反应放大和猝灭的蛋白质。 因此，他们打算提供视紫红质如何 与双层脂质一起产生触发视觉兴奋的 脊椎动物的杆，这是膜结构功能的范例 关系和一般的信号转导。

DESCRIPTION: The major goal of this research is to investigate the molecular basis for the triggering of a visual nerve impulse by the vertebrate rod. Knowledge of these molecular mechanisms can provide a conceptual basis for eventual therapeutic intervention with regard to visual disorders. The rod comprises a supramolecular assembly, in which the retinal disk membranes contain rhodopsin, an integral membrane protein, together with characteristic bilayer lipids whose composition is tightly regulated. The key signal transducing event in vision is the metarhodopsin I to metarhodopsin II conformational transition. They will test the hypothesis that upon photoexcitation of rhodopsin, the retinal Schiff base of Lys-296 is deprotonated, leading to breakage of the salt bridge to Glu-113 , which is propagated to the cytoplasmic loops of the receptor. As a result, the Meta I-Meta II transition is sensitive to the deformation energy of the membrane lipid bilayer. Diseases such as retinitis pigmentosa (RP) may be associated with perturbation of the Meta I-Meta II equilibrium, due either to mutation of rhodopsin, or alteration of the bilayer lipid environment. Two complementary biophysical methods will be employed: deuterium (2H) NMR spectroscopy and surface plasmon resonance (SPR) spectroscopy. (i) 2H NMR spectroscopy will investigate the role of the bilayer deformation energy in enabling the Meta I-Meta II conformation change of rhodopsin to occur, due to area or curvature frustration of the membrane free energy. (ii) The retinal chromophore of rhodopsin will be 2H-labeled, and 2H NMR studies will be conducted to elucidate the conformation and orientation of the retinal chromophore in the dark state. They will then investigate the changes that occur upon photoexcitation, leading to movement of the transmembrane helices and formation of the activated Meta II state. (iii) SPR spectroscopy of rhodopsin in supported planar bilayers will be used to determine how the rigid body movement of the helices influences the cytoplasmic loops of the receptor, yielding the exposure of recognition sites for the G protein (transducin). Additional SPR studies will investigate the binding constants and signaling states of the proteins involved in amplification and quenching of the visual response. Thus they intend to provide a comprehensive picture of how rhodopsin together with the bilayer lipids yields triggering of visual excitation in the vertebrate rod, which is a paradigm for membrane structure-function relationships and signal transduction in general.