PRODUCT MEDIATED REGULATION OF ORNITHINE DECARBOXYLASE

因为短寿命的蛋白质控制着生长等细胞过程 分化和肿瘤发生，我们需要了解它们是如何 被识别和降级。鸟氨酸脱羧酶(ODC)是最重要的 细胞蛋白质不稳定。它是生物合成中的关键酶。 多胺，生命所必需的分子。精致多样的蜂窝 机制控制多胺的生产、分解代谢和运输。 细胞内多胺水平的增加加速了对 ODC，通过触发第二种蛋白质的产生，称为抗酶(AZ)。 AZ与ODC结合，并通过 蛋白酶体，从而提供多胺的一种反馈控制形式 泳池。该系统将作为指导和学习的典范 受调控的蛋白质降解。与X-射线合作 结晶学家，我们将确定其三维结构 ODC和AZ，以便更好地了解它们的结构域。 我们将创造突变和嵌合蛋白，以确定 功能域，使AZ能够将ODC指定为 并确定这些域是否保留了它们的 当与不同的蛋白质相关时的功能特性。这个 蛋白酶体，一种细胞内的蛋白降解分子机器，由 多个多肽，降解ODC。我们将研究相互作用 在蛋白酶体、ODC和AZ之间。我们将确定是否 AZ护送ODC到蛋白酶体或激活蛋白酶体并将 确定负责关联的蛋白酶体的组成成分 使用ODC或AZ。多胺还促进酵母菌中ODC的降解。 我们将寻找和鉴定酵母突变株，在这个过程中 打乱了。我们将克隆假设的酵母蛋白的基因 BIND ODC并检查它们的监管角色。AZ可能有功能 这超出了对ODC的监管范围。找出它是否有更多 一般的细胞效应，我们会强迫其表达。通过在中执行此操作 被多胺补充的细胞，我们将确定它的 表达式创建的表型效应与其对 多胺生产。

Because short-lived proteins control such cellular processes as growth differentiation and oncogenesis, we need to understand how they are recognized and degraded. Ornithine decarboxylase (ODC) is among the most labile of cellular proteins. It is a key enzyme in the biosynthesis of polyamines, molecules essential for life. Elaborate and diverse cellular mechanisms control polyamine production, catabolism and transport. Increased intracellular levels of polyamines accelerate degradation of ODC, by triggering production of a second protein, termed antizyme (AZ). AZ binds to ODC and directs its proteolytic destruction by the proteasome, thereby providing a form of feedback control of polyamine pools. This system will serve as a model for studying directed and regulated protein degradation. In collaboration with X-ray crystallographers, we will determine the three-dimensional structure of both ODC and AZ, so as to better understand their structural domains. We will create mutant and chimeric proteins, in order to determine the functional domains that enable AZ to specify ODC as a substrate for degradation and to ascertain whether these domains retain their functional properties when associated with diverse proteins. The proteasome, an intracellular proteolytic molecular machine composed of multiple polypeptides, degrades ODC. We will study the interactions between and among the proteasome, ODC and AZ. We will determine whether AZ escorts ODC to the proteasome or activates the proteasome and will identify the constituents of the proteasome responsible for association with ODC or AZ. Polyamines also promote degradation of ODC in yeast. We will seek and characterize yeast mutants in which this process is disrupted. We will clone the genes for postulated yeast proteins that bind ODC and examines their regulatory role. AZ probably has functions that extend beyond regulation of ODC. To find out whether it has more general cellular effects, we will force its expression. By doing so in cells that are repleted with polyamines, we will determine whether its expression creates phenotypic effects independent of its effect on polyamine production.