Structural Dynamics of Retinal Binding and Release

项目总结 我们研究的长期目标是了解G蛋白通过 偶联受体(GPCRs)被激活和减弱。这些受体代表了 人类基因组，它们是大多数药物的靶标。我们的研究主要集中在 视紫红质及其附属蛋白。尽管与视觉有关的关键蛋白质的晶体结构 信号传递现在是已知的，这些蛋白质在激活过程中经历的大多数关键结构变化 而衰减在很大程度上仍是一种猜测。 特别是，我们甚至缺乏关于减弱视紫红质的动态事件的基本信息 信号，即视网膜从视蛋白结合袋中释放的机制，以及如何 视网膜结合和释放影响arrestin的结合和释放。理解这些过程是 视觉研究的基本重要性-视网膜连接的稳定性在不同的人中差异很大 视黄素，在某些视觉疾病状态下是一个因素。此外，尽管人们对 Arrestin与视紫红质结合的机制和动力学，目前尚不清楚是什么原因使arrestin在 结合，以及这种释放如何与视网膜生色团的状态相关。 在这项提议的目标I中，我们将确定视紫红质如何控制其视网膜Schiff碱的水解性 联动。在AIM II中，我们将研究视紫红质如何发生视网膜摄取和释放，使用最近的 视蛋白的结构来指导我们的研究。最后，在AIM III中，我们将使用我们的新方法来跟进 我们在上一个资助期间的发现--arrestin可以与MIII视紫红质结合，从而捕获和 防止视网膜释放。了解arrestin如何调节视网膜释放对于 健康，因为arrestin可以在强光条件下限制游离视网膜的释放，从而帮助限制 视网膜氧化加合物的形成可能导致老年性黄斑萎缩等疾病 退行性变(AMD)。同样，理解是什么让arrestin在与视紫红质结合后“松开”也是 关键稳定的视紫红质-arrestin复合体被认为是细胞凋亡和 常染色体显性遗传性视网膜色素变性(ADRP)。

PROJECT SUMMARY The long-term goal of our research is to understand the molecular mechanisms through which G-protein coupled receptors (GPCRs) are activated and attenuated. These receptors represent the largest family in the human genome, and they are the target of most pharmaceutical drugs. We focus our studies primarily on the GPCR rhodopsin and its affiliate proteins. Although crystal structures of key proteins involved in visual signaling are now known, most of the critical structural changes these proteins undergo during their activation and attenuation remain largely a matter of speculation. In particular, we lack even rudimentary information about the dynamic events involved in attenuating rhodopsin signaling, namely, the mechanisms through which retinal is released from the opsin-binding pocket, and how retinal binding and release affects arrestin binding and release. Understanding these processes is of fundamental importance for vision research - the stability of the retinal linkage varies widely among different opsins and is a factor in some visual disease states. Furthermore, although much is known about the mechanism and kinetics of arrestin binding to rhodopsin, little is known about what makes arrestin release after binding, and how this release is related to the status of the retinal chromophore. In Aim I of this proposal we will determine how rhodopsin controls the hydrolysis of its retinal Schiff base linkage. In Aim II we will examine how retinal uptake and release occurs in rhodopsin, using the recent structure of opsin to guide our studies. Finally, in Aim III, we will use our novel methods to follow up on a discovery we made during the last funding period - that arrestin can bind to MIII rhodopsin, thus trapping and preventing retinal release. Understanding how arrestin regulates retinal release is fundamentally important to health, as arrestin may serve to limit the release of free retinal under bright light conditions, and thus help limit the formation of oxidative retinal adducts that can contribute to diseases like atrophic age-related macular degeneration (AMD). Similarly, understanding what makes arrestin "let go" after binding rhodopsin is also crucial - stable rhodopsin-arrestin complexes have been suggested to be a contributing factor in apoptosis and autosomal dominant retinitis pigmentosa (ADRP).