BIOCHEMISTRY AND GENETICS OF MAMMALIAN/APRT

我们将继续研究突变的机制。 中国仓鼠、小鼠和人类细胞系中的aprt基因座。 突变株的分析将通过DNA测序进行，以及 与突变蛋白的比较研究。其中 致突变作用，我们有兴趣研究的影响 非整倍体剂，据报道会导致高水平的 该基因座突变的频率。体内诱变将是 与体外诱变研究平行。规管 家政基因的转录和翻译将是 以APRT为模型进行了研究。这将由一个 CAT启动子区域的缺失作图组合 用aprt基因的启动子片段与 并对该基因上的DNA结合位点进行了分析。这个 增强子元件和病毒Ltrs对APRT表达的影响 将会被检查。我们将分析将 激素调控下的aprt基因转录、翻译、 和核苷酸池。 大肠杆菌磷酸核糖基转移酶的比较分析， 果蝇、黑腹果蝇和哺乳动物来源广泛 氨基酸同源。我们将对酵母aprt基因进行测序， 并比较核苷酸和氨基酸序列。使用 比较序列分析、体外诱变、 和单抗相互作用，我们将定义 蛋白质的功能结构域。

We shall continue invistigating the mechanism of mutation at the APRT locus in Chinese hamster, mouse, and human cell lines. Analysis of mutants will be done by DNA sequencing, and comparative studies with the mutated proteins. Among mutagenic effects, we are interested in studying the effect of aneuploidizing agents, which have been reported to cause a high frequency of mutations at this locus. In vivo mutagenesis will be paralleled by studies with in vitro mutagenesis. Regulation of transcription and translation of 'house keeping' genes will be studied using APRT as a model. This will be done by a combination of deletion mapping in the promoter region, CAT assays with promoter segments of the APRT gene linked to the CAT gene, and by analysis of DNA binding sites on the gene. The effect of enhancer elements and viral LTRs on APRT expression will be examined. We shall analyze the effect of placing the APRT gene under hormonal control on transcription, translation, and nucleotide pools. Comparative analysis of phosphoribosyltransferases from E. coli, Drosophila melanogaster, and mammalian sources show extensive aminoacid homology. We shall sequence the yeast APRT gene, and compare the nucleotide and aminoacid sequences. Using the approach of comparative sequence analysis, in vitro mutagenesis, and monoclonal antibody interaction, we shall define the functional domains of the protein.