Deactivation mechanisms of rod phototransduction

描述(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(光转导反应)，从而产生对光的电反应。级联的激活和去激活最终限制了被转换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。这项研究的总体目标是了解关闭完整小鼠光感受器的光反应的机制。基因打靶技术将被用来操纵一组蛋白质的功能，这些蛋白质被认为在级联的失活中发挥关键作用，由此导致的单杆细胞光反应的变化将通过电记录和实时双光子成像确定的蛋白质定位的变化来确定。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进程是什么，它是如何由视紫红质激酶(GRK1)和arrestin(Arr1)之间的相互作用决定的？(2)G*-E*失活如何决定闪光反应的恢复，以及这种失活的速度如何通过突触传递到视觉功能？以及(3)改变光反应失活动力学的光适应的长期机制是什么？

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?