FUNCTION OF THE EVOLUTIONARILY CONSERVED RHO GENE FAMILY

Rho基因组成了一个进化上保守的家族 与ras癌基因家族有显著同源性。隐含的 Rho和ras蛋白的结构相似性表明，两者 家族是从一个共同的祖先基因进化而来的， 蛋白质具有共同的生化功能。在酵母中 酿酒酵母，Rho或ras中相似的突变 基因阻止正常的孢子形成对营养的反应 限制。这些和其他观察表明，Rho和RAS 蛋白质在信号转导过程中发挥作用。尽管 Rho和Ras家族之间的保守关系，初步 实验表明，Rho和ras的功能不同。 生化途径。因此，Rho和ras蛋白似乎 利用共同功能实现不同的生理功能 效果。 本项目的总体目标是确定RHO的功能 蛋白质，并评估功能相似性和 Rho和ras基因家族之间的差异。酵母菌 基因RHO1将是研究的初始对象，因为 初步结果表明它参与了细胞反应 对环境的影响。将使用两种互补的方法 同时研究RHO1的功能。首先，蛋白质 将被提纯并在体外进行生化鉴定。这个 这些研究的最终目的是在体外重建一个 功能正常的RHO1信号转导系统。第二 方法将使用可用的技术分离特定的 酵母基因组的区域，将这种材料改造成所需的 规范，并将更改后的DNA重新插入 染色体。这种方法将寻求在体内构建一种 用于检测RHO1功能的系统，通过使用 条件致死等位基因。遗传方法还将 研究RHO1相互作用的生化途径， 通过对第二位抑制因子的鉴定和分离 调节RHO1功能的突变。这些基因 实验将通过以下方式补充生化研究 表明RHO1的特异性活性有待体外测试。Rho 基因将在异源系统中进行功能检查，因此 揭示蛋白质家族是否在功能上 在进化中保守。除了这项一般性调查之外 Rho活性，Rho特定区域的功能关系 和ras蛋白将通过构建嵌合体进行检测。 含有ras-rho两个区段的基因 超级大家庭。

The rho genes comprise an evolutionarily conserved family with significant homology to the ras oncogene family. The implied structural similarity of rho and ras proteins suggests that the two families evolved from a common ancestral gene, and that the proteins share common biochemical functions. In the yeast Saccharomyces cerevisiae, similar mutations in either rho or ras genes prevent the normal sporulation response to nutrient limitation. These and other observations suggest that rho and ras proteins function in signal transduction processes. Despite the conservation between the rho and ras families, preliminarily experiments have shown that rho and ras function in distinct biochemical pathways. Therefore, rho and ras proteins appear to utilize common functions to achieve different physiological effects. The overall goal of this project is to determine the function of rho proteins and to evaluate the functional similarities and differences between the rho and ras gene families. The yeast gene RHO1 will be the initial subject of the studies, due to preliminary results indicating its involvement in cellular response to the environment. Two complementary approaches will be used simultaneously to investigate RHO1 function. First, the protein will be purified and biochemically characterized in vitro. The eventual aim of these studies is the reconstruction in vitro of a functional RHO1 signal transduction system. The second approach will use the techniques available for isolating specific regions of the yeast genome, engineering this material to desired specifications, and reinserting the altered DNA into the chromosome. This approach will seek to construct an in vivo system for assay of RHO1 function, through the use of conditional-lethal alleles. The genetic approach will also investigate biochemical pathways with which RHO1 interacts, through the identification and isolation of second-site suppressor mutations that modulate RHO1 function. These genetic experiments will complement the biochemical studies by indicating specific RHO1 activities to be tested in vitro. rho genes will be examined for function in heterologous systems, thus revealing whether the family of proteins has been functionally conserved in evolution. In addition to this general investigation of rho activity, the functional relationship of specific regions of rho and ras proteins will be examined by construction of chimeric genes containing domains from both divisions of the ras-rho superfamily.