PHOTORECEPTION AND TRANSDUCTIONS IN VISION

该申请概述了研究以检查分子基础的 哺乳动物视网膜视锥感光细胞的视觉信号。圆锥体 使用cGMP级联途径的信号，类似于Rod 光感受器；它们不同于杆的灵敏度、速率和 信号的幅度和适应特性。代替 生化方法，成分的鉴定将被确定 通过分子克隆，将检测它们的功能特性 随后进行体外表达。在之前的研究期间，我们有 鉴定和鉴定编码这些成分的cDNA和基因 视杆中的视觉信号。我们在这一学期的具体目标是使用 一组杆状基因作为探针来鉴定和表征 在红色/绿色视锥中参与信号传递的同源成分 还有蓝色的圆锥体。将确定潜在的锥体cDNA候选者 通过同源克隆技术。它们独特的锥体类型 鉴定将通过原位杂交研究来确定。检视 锥体信号蛋白的结构和功能 将在真核宿主细胞中表达。比较功能 将进行杆状、红/绿锥体和蓝锥体组件的研究 通过检查漂白情况和活化程度来检测OPTINS G蛋白。CGMP磷酸二酯酶的功能差异 在视杆和视锥中，将在由视黄素和视锥重建的系统中进行研究 G蛋白。视杆细胞和视锥细胞cGMP依赖的电势差异 将对脂质中的通道和Na+/Ca2+交换器进行生化检查 囊泡通透性测定。 我们试图提供关于我们最频繁使用的 对光感受器知之甚少。基因的鉴定 在锥体细胞类型中的表达及其基因特征 产品是定义圆锥体功能的第一步。这个 研究将提供工具来调查黄斑的潜在基础 影响视锥细胞的变性和视网膜变性。这个 基因结构的表征将使我们和他人能够 研究人员将对发育的分子基础进行研究 了解视杆和视锥，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.