FUNCTIONAL ANALYSIS OF THE PHOTORECEPTOR RIM PROTEIN

所有脊椎动物的光感受器都有一个外节，由 一堆紧密排列的精确排列的膜状视盘。他们的反应 在这些视盘的表面上发生视觉转导。很少 已知外段的生化决定因素 结构。通过电子显微镜分析，出现了一个关键事件 是盘状边缘的形成。几年前，一个很高的 鉴定了相对分子质量、完整膜糖蛋白 其分布限于外段盘的边缘。这 RIM蛋白是目前提案的重点。我们将利用一个 生化、细胞生物学和遗传学的综合战略 确定RIM蛋白功能的技术 光感受器外节。我们最近克隆了一种新的基因 以及在小鼠和牛视网膜中编码边缘蛋白的基因。这 研究涉及以下具体问题：(A)什么是领域 RIM蛋白的结构和膜拓扑结构？(B)是边缘 负责观察到的超微结构连接的蛋白质 在相邻圆盘的边缘之间？(C)或者，它是否进行调解 观察到的圆盘边缘和等离子体之间的联系 膜通过与细胞骨架的相互作用？(D)若有，原因为何 细胞骨架蛋白存在于外节段吗？(E)边框 蛋白质与其他已知的盘沿蛋白质相互作用， Rds/外周蛋白和rom-I？(/)哪些额外的外段蛋白？ 与边缘蛋白相互作用？ G)其光依赖的磷酸化作用是什么？(H)什么 是由于缺乏RIM蛋白而导致的表型 正在发展和成熟的外部部分？和(I)是人类中的任何一个 RIM蛋白突变引起的遗传性视网膜营养不良 吉恩？

All vertebrate photoreceptors contain an outer segment, consisting of a dense stack of precisely aligned membranous discs. The reactions of visual transduction occur on the surfaces of these discs. Very little is known about the biochemical determinants of outer segment structure. By electron microscopic analysis, a critical event appears to be formation of the disc rim. A number of years ago, a high molecular weight, integral-membrane glycoprotein was identified with a distribution restricted to the rims of outer segment discs. This rim protein is the focus of the current proposal. We will utilize an integrated strategy of biochemical, cell biological, and genetic techniques to determine the function of the rim protein in photoreceptor outer segments. We have recently cloned the mRNA and gene encoding the rim protein in mouse and bovine retina. This study addresses the specific questions: (a) what is the domain structure and membrane topology of the rim protein? (b) is the rim protein responsible for the observed ultrastructural connections between the rims of adjacent discs? (c) alternatively, does it mediate the observed connections between the disc rim and the plasma membrane through interactions with the cytoskeleton? (d) if so, what cytoskeletal proteins are present in outer segments? (e) does the rim protein interact with the other known disc rim proteins, rds/peripherin and rom-I? (/)what additional outer segment proteins interact with the rim protein? g) what is the role of its light-dependent phosphorylation? (h) what is the phenotype that results from absence of the rim protein in developing and mature outer segments? and (i) are any of the human inherited retinal dystrophies caused by mutations in the rim protein gene?