REGULATION OF VISUAL SIGNAL TRANSDUCTION BY PHOSDUCIN

描述（改编自申请人的摘要）：证据表明，磷蛋白，糖蛋白，是许多G蛋白系统的调节剂，包括脊椎动物光感受器中的视觉信号转导。这项研究的长期目标是了解光感受器和其他细胞中G蛋白的调节的精确机制。Phosducin作用于G蛋白的β/γ复合物以抑制其在G蛋白α亚基和效应蛋白的活化中的功能。当糖蛋白被磷酸化时，它不影响这些功能。这种提出的糖蛋白作用机制被称为G β/γ螯合模型。（1）测试G β/γ隔离模型对完整视杆细胞电生理反应的预测，以确定体外观察到的葡聚糖对G β/γ的作用是否在体内也起作用;（2）在结构上确定Pducin如何通过磷酸化失活和（3）表征决定Pducin磷酸化状态的细胞因子。实现这些目标的方法是多学科的。它们包括生物化学技术，用于测量磷酸化依赖性的变化，在padducin结构，定点诱变的关键padducin残基，合作电生理学研究的条件下，高和低padducin活动和生物化学测量多巴胺对padducin活动的影响。G蛋白通路组分的缺陷导致视网膜病和其他非视网膜疾病。 因此，必须了解G蛋白信号传导如何工作，以确定这些疾病的原因并开发治疗方法。这些研究有助于解决G蛋白的作用，G蛋白的功能，在G蛋白通路的调节。

DESCRIPTION (Adapted from applicant's abstract): Evidence suggests that the phospho-protein, phosducin, is a regulator of many G protein systems, including visual signal transduction in vertebrate photoreceptors. The long-term objective of this research is to understand the precise mechanism of phosducin regulation of G proteins in photoreceptors and other cells. Phosducin acts on the beta/gamma complex of G proteins to inhibit its function in the activation of G protein alpha subunits and effector proteins. When phosducin is phosphorylated, it does not affect these functions. This proposed mechanism of phosducin action has been termed the G beta/gamma sequestration model. The specific aims of this proposal are designed to test this model by: (1) testing the predictions of the G beta/gamma sequestration model on the electrophysiological responses of intact rods to determine if the effects of phosducin on G beta/gamma observed in vitro are also functional in vivo; (2) determining structurally how phosducin is inactivated by phosphorylation and (3) characterizing the cellular factors that determine the phosphorylation state of phosducin. The methods to be employed to achieve these aims are multi-disciplinary. They include biochemical techniques for measuring phosphorylation-dependent changes in phosducin structure, site-directed mutagenesis of key phosducin residues, collaborative electrophysiological studies under conditions of high and low phosducin activity and biochemical measurements of the effect of dopamine on phosducin activity. Defects in G protein pathway components cause retinopathies and other non-retinal diseases. Therefore, it is imperative to understand how G protein signaling works in order to identify the causes of such diseases and develop treatments. These studies contribute to the understanding of G protein function by addressing the role of phosducin in G protein pathway regulation.