FUNCTIONAL ANALYSIS OF THE PHOTORECEPTOR RIM PROTEIN

所有脊椎动物的光感受器都含有一个外节， 一堆紧密排列的膜盘。的反应 在这些圆盘的表面发生视觉传导。很少 已知外节的生化决定因素 结构通过电子显微镜分析， 以形成盘缘。几年前，高 分子量，完整的膜糖蛋白进行了鉴定 其分布局限于外段盘的边缘。这 rim蛋白是目前提案的重点。我们将利用一个 生物化学、细胞生物学和遗传学的综合战略 确定边缘蛋白功能的技术 光感受器外节。我们最近克隆了 以及小鼠和牛视网膜中编码rim蛋白的基因。这 本研究针对的是以下具体问题：（a）什么是 结构和膜拓扑结构的rim蛋白？(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，它是否介导 观察到的圆盘边缘和等离子体之间的连接 通过与细胞骨架的相互作用来破坏细胞膜？(d)如果是，是什么 细胞骨架蛋白存在于外节？(e)边缘是否 蛋白质与其它已知的盘缘蛋白质相互作用， rds/peripherin和rom-I？（/）哪些额外的外节蛋白质 与rim蛋白相互作用 g）其光依赖性磷酸化的作用是什么？(h)什么 是由于缺乏rim蛋白导致的表型， 发育和成熟的外节？（i）任何人， 由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?