RUI: Regulation of Beta-Adrenergic Receptor Kinase

Sterne-Marr G蛋白偶联受体是将光和激素信号转化为细胞内信息的膜结合蛋白。受体与其直接下游信号换能器G蛋白的解偶联在暴露于刺激后迅速发生，并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，ARK处于非活性状态。当受体被激素激活后，激酶的催化活性受到刺激，受体被磷酸化，导致脱敏。ARK的结构、维持预活性激酶基本状态的分子相互作用以及将预活性激酶转化为活性酶的构象变化尚不清楚。该项目的目标是了解ARK蛋白内部的相互作用如何使该分子保持非活性形式，以及ARK与激素刺激受体之间的相互作用如何诱导ARK激活。质谱、化学交联和随机靶向诱变技术将用于鉴定ARK中使该蛋白保持前活性形式的氨基酸。融合蛋白、定点诱变、酶测定和ARK /受体结合测定将用于鉴定与受体相互作用的区域。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，为研究这类蛋白的结构和活化提供了很好的模型。激素或神经递质与靶细胞表面的特定受体相互作用，引发化学信号事件。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，并发生特异性反应。为了终止特定蛋白质的信号，肾上腺素能受体激酶（ARK）在受体上添加一个磷酸基团。这项研究是针对这种蛋白质被激活并与受体相互作用的机制。这些研究将为这类蛋白的活化提供新的信息。＊＊＊

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. ***