Functions of mRNP Proteins in the Process of Translation

mRNA翻译的调控是一个重要方面 在哺乳动物细胞基因表达的控制中。 最 翻译控制的例子包括调节 蛋白质合成的起始阶段。 两种引发 事件可以区分为以下两种：1） 在多聚核糖体上起始，从而维持完整的补体 核糖体上的mRNA;和2）启动信使 核糖核蛋白（mRNP）颗粒，从而动员非- 将活性mRNA转化为活性多聚核糖体。 后一个事件是 不太了解，但它的监管遇到了 频繁 PI建议表征蛋白质， mRNP粒子并掩盖其活性。 一个这样 在Pushchino中已经纯化了50 kDa的蛋白质，其 作为翻译抑制剂的作用机制将是 试探 将确定其与mRNA结合的位点， 将鉴定蛋白质合成的抑制步骤。 他们还计划克隆其cDNA，并确定 在转染的哺乳动物细胞中过表达。 初步 来自Puschino的证据表明，50 kDa蛋白质可能 它本身由一个“激活器”调节;这个“激活器”将 进行纯化和鉴定。 这些研究依赖于经典的 蛋白质纯化和化学的生物化学技术 目前在Davis和Puschino中使用， 无细胞培养系统，一些高度分级， 用来自Davis的纯化启动因子重建，并且 使用最先进的转染方法。 %%% 该项目旨在揭示基本的分子 mRNP颗粒如何被激活和抑制的机制 翻译，因此应该有助于阐明这一重大 对基因调控知之甚少。

Regulation of mRNA translation constitutes an important aspect in the control of gene expression mammalian cells. Most examples of translational control involve modulation of the initiation phase of protein synthesis. Two kinds of initiation events can be distinguished either of which may be regulated: 1) initiation on polysomes, thereby maintaining a full complement of ribosomes on the mRNAs; and 2) initiation on messenger ribonucleoprotein (mRNP) particles, thereby mobilizing non- active mRNAs into active polysomes. The latter event is poorly understand, yet its regulation is encountered frequently. The PIs propose to characterize proteins that bind to mRNP particles and that mask their activiies. One such protein of 50 kDa has been purified in Pushchino, and its mechanism of action as a translational inhibitor will be probed. Its site of binding to mRNAs will be determined, and the inhibited step of protein synthesis will be identified. They also plan to clone its cDNA and determine the effect of overexpression in transfected mammalian cells. Preliminary evidence from Puschino suggests that the 50 kDa protein may itself be regulated by an "activator"; the "activator" will be purified and characterized. These studies rely on classical biochemical techniques of protein purification and chemistry presently used in both Davis and Puschino, employ in vitro cell-free translatiion systems, some highly fractionated and reconstituted with purified initiatiion factors from Davis, and employ state-of-the-art transfection methods. %%% The project is designed to shed light on the basic molecular mechanisms of how mRNP particles are activated and inhibited for translation, and thus should help elucidate this major poorly understood area of gene regulation.