STRUCTURAL STUDIES OF ARRESTIN AND RHODOPSIN PHOSPHATASE

拟议研究的长期目标是了解 参与淬灭的蛋白质的分子特性 光传导 三种蛋白质参与了导致 光解视紫红质的失活：视紫红质激酶、抑制蛋白和 视紫红质磷酸酶 首先，视紫红质激酶催化 新漂白的视紫红质的磷酸化， 光解的视紫红质失活，然后抑制蛋白和视紫红质 磷酸酶参与随后的失活步骤。 与激酶相反， 关于抑制蛋白在光传导中的作用， 身份 在许多视网膜变性的病例中， 疾病似乎是一种异常的周期性GMT代谢， 视紫红质基因突变;或者， 当视紫红质的水平 磷酸化/去磷酸化异常。 来定义分子 人类复杂视网膜变性的基础事件，例如 视网膜色素变性，光转导的各个步骤，因此必须 在一个非常详细的层面上确定。 计划实验的目的是（1）阐明 抑制蛋白的晶体结构(2)来调查 视紫红质的发色团时，抑制蛋白是从释放 当视紫红质被磷酸化的膜去磷酸化时， 视紫红质磷酸酶(3)以确定竞争性抑制剂的 视紫红质-抑制蛋白相互作用(4)为了表征β-抑制蛋白， 抑制蛋白的同系物，包括其功能和免疫学特性。 (5)以明确确定视紫红质磷酸酶和 其活动。

The long-term objective of the proposed studies is to understand the molecular properties of the proteins involved in quenching phototransduction. Three proteins are engaged in the process that leads to deactivation of photolyzed rhodopsin: rhodopsin kinase, arrestin and rhodopsin phosphatase. First, rhodopsin kinase catalyzes the phosphorylation of freshly bleached rhodopsin which initiates the deactivation of photolyzed rhodopsin, and then arrestin and rhodopsin phosphatase are involved in the subsequent deactivation steps. In contrast to kinase, only fragmentary information is available about the role arrestin has in phototransduction and about the phosphatase identity. In many cases of retinal degeneration, the primary causes of the disorder appear to be either an abnormality cyclic GMT metabolism or mutations in the rhodopsin gene; alternatively, the degeneration of photoreceptor cells becomes evident when levels of rhodopsin phosphorylation/dephosphorylation are abnormal. To define the molecular events that underlie a complex retinal degeneration in humans, such as retinitis pigmentosa, the various steps of phototransduction therefore must be determined on a very detailed level. The objectives of the planned experiments are (1) to elucidate the crystallographic structure of arrestin. (2) to investigate the status of rhodopsin's chromophore when arrestin is released from the phosphorylated membranes and when rhodopsin is dephosphorylated by rhodopsin phosphatase. (3) to identify competitive inhibitors of the rhodopsin-arrestin interaction. (4) to characterize beta-arrestin, a homolog of arrestin, including its functional and immunological properties. (5) to definitively identify the rhodopsin phosphatase and an inhibitor of its activity.