Deactivation mechanisms of rod phototransduction

描述（由申请人提供）：视网膜视杆细胞和视锥细胞对光子的吸收激活了一系列生化反应（光转导级联），产生对光的电反应。级联的激活和失活最终限制了转导信号的幅度和动力学，从而限制了视觉的灵敏度和时间分辨率。本研究的总体目标是了解关闭完整小鼠光感受器光反应的机制。基因靶向技术将被用来操纵一个子集的蛋白质，已建议发挥关键作用的级联失活的功能，并在单杆细胞的光响应所产生的变化将确定通过电记录和蛋白质定位的变化确定的实时2-光子成像。使用这些方法，我们将解决三个重要的问题：（1）视紫红质失活的时间过程是什么，它是如何决定的视紫红质激酶（GRK 1）和arrestin（Arr 1）之间的相互作用？(2)G*-E* 失活是如何决定闪光反应的恢复的？改变这种失活的速率是如何通过突触传递影响视觉功能的？以及（3）改变光响应失活动力学的光适应的持久机制是什么？

DESCRIPTION (provided by applicant): The absorption of photons in rods and cones of the retina activates a cascade of biochemical reactions (phototransduction cascade) that generates the electrical response to light. The activation and deactivation of the cascade ultimately limits the amplitude and kinetics of the transduced signal, and thus the sensitivity and temporal resolution of vision. The overall goal of this study is to understand the mechanisms that turn off the light response in intact mouse photoreceptors. Gene targeting techniques will be used to manipulate the function of a subset of proteins that have been suggested to play key roles in deactivation of the cascade, and the resulting changes in the photoresponses of single rod cells will be determined by electrical recording and changes in protein localization determined by real-time 2-photon imaging. Using these approaches, we will address three important questions: (1) What is the time course of rhodopsin deactivation, and how is it determined by the interactions between rhodopsin kinase (GRK1) and arrestin (Arr1)? (2) How does G*-E* deactivation determine recovery of the flash response, and how does changing the rate of this deactivation get relayed across the synapse to affect visual function? and (3) What are the long-lasting mechanisms of light adaptation that alter the kinetics of photoresponse deactivation?