Regulation of Rhabdomere Assembly: Opsin and Chromophore

这项研究项目解决了视觉和光接收细胞生物学中的一个中心问题：光敏膜及其组成的光敏分子(视紫红质)周转的机制和意义。在正常和缺乏维生素A的情况下，人们正在研究光感受器中光敏膜的组装。作为光敏膜前体的细胞内膜在缺乏维生素A的光感受器中以大量物质的形式积累。当这些细胞暴露在非常明亮的光线下，以补偿它们的相对不敏感时，内层膜会迅速添加到光敏膜上。该实验室还在测试一种假说，即参与光反应的生化途径与光感受器中光敏感膜的组装和降解的调节之间的关系。正在使用的技术包括专门模拟生化途径中的各种步骤的药理学试剂。这些试剂对光感受器细胞的结构影响将用电子显微镜进行研究。功能效应将通过电生理方法进行评估。维生素A衍生物进入视网膜并被视网膜利用来为光接收提供光敏分子的途径也在研究中。

This research project addresses a central issue in the cell biology of vision and photoreception: the mechanisms and significance of turnover of light- sensitive membrane and its constituent light-sensitive molecule (rhodopsin). The assembly of light-sensitive membranes in light receptors are being studied in the normal and also in the vitamin-A deprived condition. Intracellular membranes that serve as the precursors of photosensitive membranes accumulate as large masses within vitamin-A deficient photoreceptors. When such cells are exposed to very bright light that compensates for their relative insensitivity, the internal membrane is rapidly added to the light-sensitive membrane. This laboratory also is testing an hypothesis concerning the relationship between the biochemical pathway that is involved in the response to light and the regulation of assembly and degradation of the light-sensitive membrane in photoreceptors. Techniques being used include pharmacological agents that specifically mimic various steps in the biochemical pathway. The structural effects of these agents on photoreceptor cells will be studied with electron microscopy. Functional effects will be assessed with electrophysiological methods. The pathway by which vitamin A derivatives enter and are utilized by the retina to provide the light-sensitive molecules for photoreception is also being investigated.