PHOTORECEPTION AND TRANSDUCTION IN VISION

该申请概述了研究，以检查的分子基础， 哺乳动物视网膜的视锥光感受器中的视觉信号。 锥 使用类似于视杆细胞cGMP级联途径的信号传导 光感受器;它们在敏感性、速率和 信号幅度和适应特性。 代替 通过生物化学方法，将确定组分的身份 通过分子克隆;它们的功能特性将被检查 在体外表达后。 在过去的研究中，我们 鉴定并表征了编码这些组分的cDNA和基因， 视杆细胞的视觉信号。 我们在这个术语中的具体目标是使用 视杆细胞基因组作为探针， 有助于红/绿色视锥细胞中信号传导的同源组分 和蓝色锥体。 锥cDNA的潜在候选者将被鉴定 通过同源克隆技术。 它们特有的视锥细胞类型 通过原位杂交研究确定同一性。 审查 视锥细胞信号蛋白的结构和功能， 将在真核宿主细胞中表达。 比较泛函 将对棒、红/绿色锥和蓝锥成分进行研究 通过检查漂白曲线和激活， G蛋白 cGMP磷酸二酯酶的功能差异 将在用视蛋白重建的系统中研究视杆细胞和视锥细胞中的蛋白质， G蛋白 视杆细胞和视锥细胞cGMP依赖的电位差 通道和Na+/Ca 2+交换器将在脂质中进行生化检查 囊泡通量测定。 我们寻求提供有关我们最密集使用的基本信息， 和最不了解的光感受器。 基因的鉴定 在视锥细胞类型中表达及其基因的表征 产品是定义视锥细胞功能的第一步。 的 研究将提供工具来调查黄斑病变的潜在基础， 影响视锥细胞的变性和视网膜变性。 的 基因结构的表征将使我们和其他人 研究人员对发展的分子基础进行研究 并最终了解发育中的缺陷。

The application outlines studies to examine the molecular basis of visual signalling in cone photoreceptors of the mammalian retina. Cones signal using a cGMP cascade pathway similar to that of rod photoreceptors; they differ from rods in their sensitivity, rate and amplitude of signaling, and adaptation properties. In lieu of biochemical methods, the identity of the components will be established through molecular cloning; their functional properties will be examined following in vitro expression. In previous research periods, we have identified and characterized the cDNAs and genes encoding the components of visual signaling in rods. Our specific aims in this term are to use the set of rod genes as probes to identify and characterize the homologous components that contribute to signaling in the red/green cones and blue cones. Potential candidates for cone cDNAs will be identified through the technique of homology cloning. Their specific cone-type identity will be determined by in situ hybridization studies. To examine the structure and function of cone signaling proteins, the components will be expressed in eucaryotic host cells. Comparative functional studies for rod, red/green cone and blue cone components will be carried out for the opsins by examination of the bleaching profile and activation of G-proteins. The differences in functioning of cGMP phosphodiesterases in rod and cones will be studied in systems reconstituted with opsins and G-proteins. The potential differences in rod and cone cGMP-dependent channels and Na+/Ca2+ exchangers will be examined biochemically in lipid vesicle flux assays. We seek to provide basic information about our most intensively used and least understood photoreceptors. The identification of genes expressed in cone cell types and the characterization of their gene products is a first step towards defining how cones function. The studies will provide tools to investigate the underlying basis of macular degeneration and retinal degenerations that affect cone cells. The characterization of gene structure will enable ourselves and other investigators to undertake studies of the molecular basis of development of rods and cones and ultimately to understand defects in development.