Ankyrin G in protein sorting between rod plasma membrane and photoreceptor discs

描述（由申请人提供）：本申请的总体目标是探索膜细胞骨架在光感受器外节功能中的作用。膜细胞骨架装饰基本上所有细胞类型中的质膜，为它们提供机械支持并将选定的膜蛋白保留在专门的膜子域内。令人惊讶的是，膜细胞骨架在光感受器中的作用直到最近才得到系统的解决，当时我们报道了环核苷酸门控通道2-亚基的外段靶向关键取决于其与膜细胞骨架蛋白锚蛋白G的相互作用。我们现在提出锚蛋白G的另一个主要功能是将该通道和其他蛋白质保留在视杆细胞外节质膜上，并防止它们分选到感光盘中。在目标1中，我们将测试环核苷酸门控通道的情况下，这一假设。在目标2中，我们将在杆外节中寻找其他锚蛋白G结合伴侣。我们也将测试视杆细胞中其他蛋白质的选择性质膜定位是否依赖于它们与锚蛋白G的结合。我们希望这项探索性研究的完成将产生足够的信息，概念和实验工具，以建立一个更大的计划，致力于了解感光细胞健康和疾病的膜细胞骨架的作用。 公共卫生相关性：本申请中提出的研究解决了负责感光细胞的光敏区室（外节）的生物发生、维持和功能的分子和细胞机制。这些过程的功能障碍导致一些最严重类型的遗传性视网膜变性疾病，包括但不限于色素性视网膜炎。这凸显了了解蛋白质运输到外节及其随后组装成大型功能复合物的机制的重要性。阐明这些机制对于制定疾病预防和未来治疗干预策略至关重要。

DESCRIPTION (provided by applicant): The overall goal of this application is to explore the role of the membrane cytoskeleton in the functioning of photoreceptor outer segments. The membrane cytoskeleton decorates plasma membranes in essentially all cell types, providing them with mechanical support and retaining selected membrane proteins within specialized membrane sub-domains. Surprisingly, the role of the membrane cytoskeleton in photoreceptors had not been systematically addressed until very recently, when we reported that the outer segment targeting of the 2-subunit of the cyclic nucleotide-gated channel is critically dependent on its interaction with the membrane cytoskeleton protein ankyrin G. We now propose that another major function of ankyrin G is to retain this channel and other proteins at the rod outer segment plasma membrane and to prevent them from sorting into photoreceptor discs. In Aim 1 we will test this hypothesis for the case of the cyclic nucleotide-gated channel. In Aim 2 we will search for other ankyrin G binding partners in rod outer segments. We will also test whether selective plasma membrane localization of other proteins in rods is dependent on their binding to ankyrin G. We hope that the completion of this exploratory study will yield a sufficient body of information, concepts and experimental tools to build a larger program devoted to understanding the roles of the membrane cytoskeleton in photoreceptor health and disease. PUBLIC HEALTH RELEVANCE: The studies proposed in this application address the molecular and cellular mechanisms responsible for the biogenesis, maintenance and functioning of the light-sensitive compartment of the photoreceptor cells, the outer segment. Dysfunction of these processes causes some of the most severe types of inherited degenerative diseases of the retina, including but not limited to retinitis pigmentosa. This highlights the importance of understanding the mechanisms underlying the trafficking of proteins to the outer segment and their subsequent assembly into large functional complexes. Elucidating these mechanisms is essential for developing strategies for disease prevention and future therapeutic interventions.