MOLECULAR MECHANISM OF VISUAL TRANSDUCTION

该项目的长期目标是了解分子事件 作为视觉感光细胞功能的基础，特别是 导致视觉感觉的过程，即，激发，传导， 适应和恢复敏感性。 为了实现这一 目标，果蝇，果蝇，将被用作一个主要的 实验系统在此基础上 以果蝇为模型 系统研究的一般规则的生理功能 包括人类在内的高等脊椎动物现已被广泛接受。 的 这种方法的基本原理是基于这样一个事实，即果蝇共享 许多蛋白质表现出高度的相似性， 脊椎动物 此外，果蝇是为数不多的真核系统之一， 最先进的基因和分子生物学技术 可以应用。 作为一个短期目标，本项目旨在阐明 蛋白质磷酸化在视觉光感受器功能中的作用 是 众所周知，磷脂酰肌醇特异性磷脂酶（PI-） PLC）在涉及钙离子的第二信使系统中起关键作用， 蛋白激酶C介导的过程中的各种细胞类型。 的 双翅目果蝇的光感受器转导可能涉及 激活PI-PLC。 根据我们以前项目的结果， 提出了光诱导的49 K蛋白的磷酸化， 果蝇光感受器受Ca ~（2+）的调节，Ca ~（2+）的浓度 可能会受到PI-PLC的监管。 该项目的目标是：1） 49 K蛋白的基因结构，包括cDNA的DNA序列 编码49 K蛋白质的蛋白质，将被确定。 2)49 K蛋白质 在温和条件下纯化，以检查可能的蛋白质 激酶活性和可能的Ca 2+结合。 3)部分氨基酸 将确定溴化氰切割的49 K蛋白片段的序列， 将确定连接磷酸基团的片段。 4)49 K蛋白的空间和时间（发育）表达 将通过使用抗体和RNA探针在光和 电子显微镜水平 5)在49 K蛋白基因座的突变将 为了检查49 K基因的表型表达， 当它有缺陷的时候。

The long term goal of this project is to understand the molecular events underlying the function of visual photoreceptor cells, especially the processes leading to visual sensation, i.e., excitation, transduction, adaptation, and restoration of sensitivity. In order to achieve this goal, the fruit fly, Drosophila melanogaster, will be used as a major experimental system in this proposal. The use of Drosophila as a model system to study general rules underlying the physiological functions of higher vertebrates including humans is now widely accepted. The rationale of this approach is based on the fact that Drosophila shares many proteins exhibiting a high degree of similarity with those of vertebrates. Moreover, Drosophila is one of the few eucaryotic systems in which the most advanced genetic and molecular biological techniques can be applied. As a short term goal, this project aims to elucidate the role of protein phosphorylation in visual photoreceptor function. It is well established that phosphotidylinositol-specific phospholipase (PI- PLC) plays a key role in second messenger systems involving calcium- and protein kinase C-mediated processes in a wide variety of cell types. The photoreceptor transduction of dipteran flies is likely to involve the activation of PI-PLC. Based on the results of our previous project, it is proposed that the light-induced phosphorylation of the 49K protein of Drosophila photoreceptor is regulated by Ca2+, the concentration of which is likely to be regulated by PI-PLC. The goals of the project are: 1) The gene structure of the 49K protein, including the DNA sequence of cDNA encoding the 49K protein, will be determined. 2) The 49K protein will be purified under mild conditions in order to examine possible protein kinase activity and possible Ca2+ binding. 3) Partial amino acid sequences of CNBr-cleaved 49K protein fragments will be determined and the fragment to which the phosphate group is attached will be determined. 4) Spatial and temporal (developmental) expression of the 49K protein will be examined by use of antibody and RNA probes both at light and electron microscope levels. 5) Mutations at the 49K protein locus will be created in order to examine the phenotypic expression of the 49K gene when it is defective.