The Light-Dependent Cation Channel of Fly Photoreceptors

光感受器细胞对光有一系列的反应。在脊椎动物的眼睛里，环状GMP是光感受器中的一种化合物，当细胞被照亮时，它会增加内部浓度。然后，cGMP浓度的增加会触发细胞膜上允许离子通过的通道的打开。由于离子带有电荷，它们的运动产生了被称为受体电势的电子事件。对无脊椎动物光感受器中依赖光的阳离子通道知之甚少，尽管无脊椎动物为理解这一重要特征的发育和调控的遗传基础提供了希望。果蝇，果蝇，是众所周知的它在遗传学研究中的使用，并且有各种各样的突变株可用。这个项目将研究苍蝇的光依赖阳离子通道，使用一种新开发的体外准备，允许进入细胞膜用于膜片钳记录的电生理技术。将建立通道开放和关闭的特性，并与脊椎动物光感受器的特性进行比较。将确定控制通道开放的生化化合物，以与cGMP在脊椎动物光感受器中的作用进行比较。将对果蝇的视觉突变体进行筛选，以确定决定控制这一重要膜成分的基因的结构或功能的可能基因。这项工作将直接导致基因操作的前景，允许对这些通道进行结构分析；这种对感觉转导中重要的蛋白质的分析将对所有感官科学产生重大影响。

A photoreceptor cell responds to light in a series of steps. In the vertebrate eye, cyclic GMP is a compound in the photoreceptors that increases in internal concentration when the cell is illuminated. The increased concentration of cGMP then triggers opening of channels in the cell membrane that allow ions to cross it. Since the ions carry electrical charge, their movement produces the electrical event called the receptor potential. Very little is known about the light-dependent cation channel in photoreceptors of invertebrates, although invertebrates offer the promise of understanding the genetic basis for the development and regulation of this important feature. The fruit fly, Drosophila, is well-known for its use in genetic studies, and a wide variety of mutant strains are available. This project will study light-dependent cation channel in flies, using a newly developed preparation in vitro that allows access to cell membranes for the electrophysiological technique of patch-clamp recording. The properties of channel opening and closing will be established and compared with those for vertebrate photoreceptors. Biochemical compounds will identified that control the opening of the channel to compare to the cGMP role in the vertebrate photoreceptors. Visual mutants of Drosophila will be screened to identify possible genes that determine the structure or function of the genes controlling this important membrane component. This work will lead directly to the promise of genetic manipulation allowing structural analysis of these channels; such analysis of proteins important in sensory transduction will have substantial impact on all sensory science.