RUI: Regulation of Beta-Adrenergic Receptor Kinase

9728179 Sterne-Marr G蛋白偶联受体是一种膜结合蛋白，能将光和激素信号转化为细胞内信息。在受到刺激后，受体与其直接下游的信号转导蛋白G蛋白迅速解偶联，导致对激素的反应停止(脱敏)。肾上腺素能受体激酶(ARK)的受体磷酸化是激素依赖性的，并促进G蛋白/受体解偶联。在激素治疗之前，方舟处于非活动状态。当激素激活受体时，激活酶的催化活性被激发，受体被磷酸化，导致脱敏。人们对ARK的结构知之甚少，也不知道维持前活性激酶处于基础状态的分子相互作用，以及将前活性激酶转化为活性酶的构象变化。这个项目的目标是了解ARK蛋白内部的相互作用如何使该分子保持不活跃的形式，以及ARK与激素刺激的受体之间的相互作用如何诱导ARK激活。将使用质谱学、化学交联和随机定向突变技术来鉴定ARK中使该蛋白质保持在预活性形式的氨基酸。将使用融合蛋白、定点突变、酶分析和ARK/受体结合分析来确定与受体相互作用的区域。由于ARK是调节G蛋白偶联受体的G蛋白偶联受体激酶家族的成员，它为研究这类蛋白的结构和活性提供了一个很好的模型。荷尔蒙或神经递质与靶细胞表面的特定受体相互作用，启动化学信号事件。一种被称为G蛋白的分子，因为它与GTP结合，与受体和下游信号分子相互作用，发生特定的反应。为了终止一种特定蛋白的信号，肾上腺素能受体激酶(ARK)在受体上添加了一个磷酸基团。这项研究针对的是这种蛋白被激活并与受体相互作用的机制。这些研究将提供有关这类蛋白质激活的新信息。***

9728179 Sterne-Marr G protein coupled receptors are membrane bound proteins which convert light and hormonal signals into intracellular messages. Uncoupling of the receptor from its immediate downstream signal transducer, the G protein, occurs rapidly following exposure to a stimulus and results in cessation of response to the hormone (desensitization). Receptor phosphorylation by the (adrenergic receptor kinase ( ARK) is hormone-dependent and promotes G protein/receptor uncoupling. Prior to hormone treatment ARK exists in an inactive state. Upon activation of the receptor by hormone, the catalytic activity of the kinase is stimulated and the receptor is phosphorylated, resulting in desensitization. Little is known about the structure of ARK, the molecular interactions which maintain the pre-active kinase in its basal state, and the conformation changes which convert the pre-active kinase into an active enzyme. The goals of this project are to understand how interactions within the ARK protein maintain this molecule in an inactive form and how interactions between ARK and a hormone stimulated receptor induce ARK activation. The techniques of mass spectrometry, chemical cross-linking and random targeted mutagenesis will be used to identify the amino acids in ARK which keep this protein in the pre-active form. Fusion proteins, site-directed mutagenesis, enzyme assays and ARK /receptor binding assays will be used to identify regions that interact with the receptors. Since ARK is a member of a family of G protein coupled receptor kinases which regulate G protein-coupled receptors, it provides a good model to study the structure and activation of this class of proteins. The interaction of a hormone or neurotransmitter with a specific receptor on the surface of a target cell initiates a chemical signaling event. A molecule known st a G protein, because it binds GTP, interacts with the receptor and downstream signaling molecules and a specific response occurs. To terminate the signal a specific protein, the adrenergic receptor kinase ( ARK) adds a phosphate group to the receptors. This research is directed at the mechanisms by which this protein becomes activated and interacts with the receptor. These studies will provide new information about activation of this class of proteins. ***