Molecular Biology of Steroidogenic Proteins

描述：（由申请人提供）类固醇激素是普遍存在的调节剂 是生理过程的重要组成部分，也是生命的必需品。人体产生一种 在许多组织中广泛的类固醇激素，但所有的生物合成 类固醇激素从胆固醇开始。在过去的15-20年里， 描述了类固醇生成的途径，导致识别和 类固醇生成的所有酶的表征和它们的克隆 基因.我们以前的工作支持DK 37922包括克隆和 许多这些cDNA和基因的表征，并强调了 通过研究人类， 基因突变导致的遗传疾病。我们工作的一个主要重点 在过去的6年中， （星星）。星星促进胆固醇从外到内的运动 线粒体膜，我们发现星星突变导致先天性 类脂质肾上腺增生;然而，星星的作用机制仍然存在 未知的和有争议的。为了阐明星星的作用机制， 提出五个目标。目标1： 确定星星作用的线粒体部位。我们的数据显示星星 作用于线粒体外膜（0 MM）的细胞质侧，但 其他人则认为，星星的功能介于外部和内部之间， 膜，在膜内空间。目标2：确定 星星进入线粒体的机制影响星星的活性。如果 星星作用于0 MM，其净活动应与0 MM驻留时间相关， 线粒体的输入应该会超过星星。目标3：确定追回星星 经历构象变化，同时与膜模型的相互作用， 0MM。我们已经报道，星星经历了pH依赖性的变化， 溶液中的球体形态，并与合成膜结合， 但是还不知道这是否与0 MM相关联地发生。目标4： 确定星星在结合时是否发生构象变化， 排出胆固醇。了解追回星星举措如何与 胆固醇对于了解星星如何将胆固醇从 线粒体外膜到线粒体内膜。目标5：识别结构域（序列） 与线粒体外膜相互作用的N-62星星。拓扑 目前还没有任何关于星星与Eklion相互作用的研究。 这一目标将确定星星蛋白的哪些片段 与0 MM联系。实现这五个目标将大大推动我们的 了解星星的作用机制。

DESCRIPTION: (Provided by applicant) Steroid hormones are ubiquitous regulators of physiologic processes and are essential for life. The human body makes a broad array of steroid hormones in numerous tissues but the biosynthesis of all steroid hormones begins with cholesterol. Work over the last 15-20 years has delineated the pathways of steroidogenesis, leading to the identification and characterization of all the enzymes of steroidogenesis and the cloning of their genes. Our previous work supported by DK37922 included the cloning and characterization of many of these cDNAs and genes and has emphasized the delineation of the biological role of each of these by studying the human genetic diseases that result from their mutations. A major focus of our work for the past 6 years has been the steroidogenic acute regulatory protein (StAR). StAR facilitates the movement of cholesterol from the outer to inner mitochondrial membrane, and we showed that StAR mutations cause congenital lipoid adrenal hyperplasia; however the mechanism of StAR's action remains unknown and controversial. To elucidate the mechanisms of StAR's action we propose five Aims. Aim 1: Determine the mitochondrial site of StAR's action. Our data indicate that StAR acts on the cytoplasmic side of the outer mitochondrial membrane (0MM), but others have suggested that StAR functions between the outer and inner membranes, in the intra-membranous space. Aim 2: Determine whether the mechanisms of StAR's import into the mitochondria influence StAR's activity. If StAR acts on the 0MM, its net activity should be related to 0MM residency time, and mitochondrial import should inactivate StAR. Aim 3: Determine whether StAR undergoes conformational changes while interacting with membrane models of the 0MM. We have reported that StAR undergoes a pH-dependent change to a molten globule conformation in solution, and in association with a synthetic membrane, but it is not yet known if this happens in association with the 0MM. Aim 4: Determine whether StAR undergoes conformational changes while binding and discharging cholesterol. Understanding how StAR associates with and discharges cholesterol is crucial for understanding how StAR moves cholesterol from the outer to inner mitochondrial membrane. Aim 5: Identify the domains (sequences) of N-62 StAR that interact with the outer mitochondrial membrane. The topology of StAR's interactions with the mitochondrion have not yet been explored in any published work; this aim will determine which segments of the StAR protein associate with the 0MM. Fulfilling these 5 aims will substantially advance our understanding of the mechanism of StAR's action.