STRUCTURE/FUNCTION OF SHORT WAVELENGTH VISUAL PIGMENTS

短波长视觉颜料的结构/功能

• 批准号: 2020015
• 负责人: Barry E Knox
• 金额: $ 15.81万
• 依托单位: UPSTATE MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-12-01 至 2000-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2020015
• 关键词: Xenopus; alternatives to animals in research; aminoacid; chemical models; color visions; disulfide bond; eye regeneration; immunoaffinity chromatography; infrared spectrometry; lasers; phospholipids; protein structure function; radionuclides; rhodopsin; rod cell; scintillation counter; site directed mutagenesis; thin layer chromatography; ultracentrifugation; ultraviolet spectrometry; visible light; visual phototransduction; visual pigments; western blottings

Photopic vision is mediated by cone cells, which function at high levels of illumination, respond to rapid changes in light (flicker) and permit color discrimination. Each cone cell expresses a protein, called a color or cone opsin, that determines its spectral sensitivity and response characteristics. Although the cone opsins are members of a larger family of visual pigments that bind 11-cis retinal to form the phototransduction molecule, and share significant amino acid sequence homology with the rhodopsins, the molecular mechanisms that produce the unique properties of cone pigments are not understood. Among the cone pigments, the short wavelength pigments (with wavelengths of peak absorbance, lambda-max equals approximately 415-440 nm) permit vision in the violet/blue region of the spectrum and are found ubiquitously in nature. In addition, responses of short wavelength cones to light show slower kinetics and increased sensitivity than the long wavelength (red) cones. In humans with severe red-green opsin mutations, the blue opsin is the sole mediator of photopic vision. Clearly, they form an important component of vision in most animals. The overall goal of this project is to understand the molecular mechanisms of 11-cis- retinal/short wavelength opsin interactions that bring about their unique absorbance properties and photobleaching/regeneration behavior; in particular, to determine how specific amino acid residues contribute to spectral tuning and phototransduction. Given the fundamental differences between rod and short wavelength cone physiology, it is not likely that direct extrapolation from rhodopsin will yield sufficient insight into the mechanistic divergence between these two different proteins. The specific aims of the proposal are to 1) biochemically characterize the bleaching/regeneration pathway and to study the physiologically active conformation of Xenopus violet cone opsin; 2) characterize the interaction of the short wavelength opsin with retinal using low temperature and time-resolved (>10 ns) UV-visible spectroscopy; 3) investigate the role specific amino acids in violet cone opsin have in retinal interactions, photobleaching and regeneration using molecular models coupled to site-directed mutagenesis.

光波视觉是由锥细胞介导的，锥细胞在高 照明水平，对光的快速变化（闪烁）和 允许颜色歧视。每个锥细胞都表示一种蛋白质，称为 颜色或锥蛋白，决定其光谱敏感性，并且 响应特征。虽然锥体蛋白是 较大的视觉颜料家族结合11盘视网膜以形成 光转导分子，并具有明显的氨基酸序列 与Rhodopsins的同源性，产生的分子机制 锥体色素的独特特性尚不清楚。 在圆锥体中 颜料，短波长色素（峰值波长 吸光度，lambda-max等于大约415-440 nm）允许视觉 在光谱的紫罗兰色/蓝色区域中，发现普遍存在 本质。另外，短波长锥对光的响应 比长波长显示较慢的动力学和提高灵敏度 （红色）锥。在患有严重红绿色Opsin突变的人类中，蓝色 Opsin是光波视觉的唯一介体。显然，它们形成了 大多数动物视力的重要组成部分。总体目标 项目是了解11-CIS-的分子机制 视网膜/短波长OPSIN相互作用会带来他们的 独特的吸光度和光漂白/再生行为； 特别是，确定特定氨基酸残基如何贡献 进行光谱调整和光转导。鉴于基本 杆和短波长锥体生理学之间的差异，不是 从视紫红质直接推断可能会产生足够的 深入了解这两个不同的机械差异 蛋白质。该提案的具体目的是1）生化 表征漂白/再生途径并研究 爪蟾紫锥蛋白的生理活跃构象； 2） 表征短波长Opsin与视网膜的相互作用 使用低温和时间分辨（> 10 ns）紫外线可见 光谱； 3）研究紫罗兰的特定氨基酸的作用 锥蛋白具有视网膜相互作用，光漂白和 使用分子模型再生与位置定向的分子模型 诱变。