HORMONE REGULATED ADENYLYLCYCLASE ISOFORMS

说明(改编自申请人的摘要)：规则 细胞内环磷酸腺苷浓度主要控制在 它的合成水平，通过激素调节 腺苷环化酶，负责将三磷酸腺苷转化为 环状AMP。腺苷环化酶系统由三个组分组成： 各种激素的七螺旋G蛋白偶联受体， 神经递质和自体激素；异源三聚体G蛋白；以及 催化实体本身。G蛋白调节细胞的活性 酶反应的配体与适当的相互作用 受体。这种分子结构是所有G蛋白所共有的 迄今为止发现的包括激素在内的受调控的效应系统 调节磷脂酶和离子通道，以及光 激活环状GMP磷酸二酯酶。对监管的核心 腺苷环化酶，或任何其他效应分子，是 G蛋白将适当的受体偶联到 正确的效应器。额外的监管水平是通过 不同G蛋白偶联效应系统的串扰，通常 由下游蛋白激酶的作用所介导。最近的 腺苷环化酶多种异构体的克隆使 生化证明这些环化酶受G调节 蛋白质和蛋白激酶以一种异构体特定的方式。两个人 本项目的目标是：1)确定精确的分子信号 G识别腺苷环化酶的特异性 蛋白质，以及2)表征磷酸化在蛋白质中的作用。 腺苷环化酶异构体的调节。两个遗传系统(基于 哺乳动物腺苷环化酶和G蛋白亚基的表达 酵母)将用于选择两者的调节突变体 腺苷环化酶和G蛋白亚基。突变缺陷菌株的分离 在将G蛋白亚基与腺苷环化酶偶联时，将允许探测 G蛋白识别和调控的分子基础 腺苷环化酶。此外，体外和体内方法将是 用于阐明特异性腺苷环化酶同工酶亚型的调节 磷酸化。这些研究将对 对效应器调节机制的理解 由G蛋白组成的系统和不同物种之间复杂的串扰 激素调节的信号通路。

DESCRIPTION (Adapted from the applicant's abstract): Regulation of intracellular cyclic AMP concentrations is principally controlled at the level of its synthesis, through the hormonal regulation of adenylylcyclase, the enzyme responsible for the conversion of ATP into cyclic AMP. The adenylylcyclase system is comprised of three components: heptahelical, G protein-coupled receptors for a variety of hormones, neurotransmitters, and autocoids; heterotrimeric G proteins; and the catalytic entity itself. The G proteins regulate the activity of the enzyme in response to the interaction of ligands with an appropriate receptor. This molecular architecture is common to all G protein regulated effector systems identified to date and include hormone regulated phospholipases and ion channels, as well as the light activated cyclic GMP phosphodiesterases. Central to the regulation of adenylylcyclase, or any of the other effector molecules, is the specificity of the G proteins to couple an appropriate receptor to the correct effector. An additional level of regulation is achieved by the cross-talk of different G protein-coupled effector systems, often mediated by the action of downstream protein kinases. The recent cloning of multiple isoforms of adenylylcyclases has permitted the biochemical demonstration that these cyclases are regulated by G proteins and protein kinases in an isoform specific fashion. The two aims of this project are: 1) to determine the precise molecular signals underlying the specificity of recognition of adenylylcyclase by G proteins, and 2) to characterize the role of phosphorylation in the regulation of adenylylcyclase isoforms. Two genetic system (based on the expression of mammalian adenylylcyclases and G protein subunits in yeast) will be used to select for regulatory mutants of both adenylylcyclases and G protein subunits. Isolation of mutant defective in coupling G protein subunits to adenylylcyclases will allow to probe the molecular basis of G protein recognition and regulation of adenylylcyclase. In addition, in vitro and in vivo approaches will be used to elucidate the regulation of specific adenylylcyclase isoforms by phosphorylation. These studies will have a significant impact on the understanding of the mechanisms underlying the regulation of effector systems by G proteins and the intricate cross-talk among different hormone regulated signaling pathways.