MAIZE RIBOSOMAL PROTEIN GENE STRUCTURE AND EXPRESSION

拟议研究的长期目标是 了解基因结构如何与基因表达相关；如何 细胞调节大量基因的表达以产生 功能体(70s)和胞质(80s)核糖体；以及 胞质和核编码的70S核糖体蛋白的表达 基因在不同的基因组中相互协调。大幅增加的 70s和80s核糖体的细胞含量在玉米发育过程中发生 叶细胞发育。具体目标是彻底 表征整个玉米叶片中的核糖体含量； 测定80s和编码的叶绿体和核的含量 利用核糖体编码叶片中的70S核糖体蛋白mRNAs 作为杂交探针的蛋白质cDNA；并检测 叶片中核糖体蛋白质的合成。此外， 70年代核糖体含量对核糖体基因表达的影响 编码的70秒核糖体蛋白基因的表达将在 对玉米的积累具有预冷敏感性的突变体 70年代的核糖体。这些实验旨在确定 70年代均衡积累的机制 核糖体蛋白。 与上述研究相辅相成的是对 80年代和70年代核糖体蛋白基因结构。 用异源70和80分离这些基因的cDNA 核糖体蛋白cDNA。然后，玉米的cDNA将用于 以上实验，并从一株 玉米图书馆。几个80年代和70年代的核糖体 蛋白质基因将被测序。转录开始和停止 将通过S1核酸酶作图和引物来鉴定位点 可拓分析。这些基因的计算机辅助序列分析 基因可能揭示的DNA序列可能参与 协调调节核糖体蛋白基因。蛋白 基因的结合活性将通过DNA足迹进行检测 分析。此外，一些核糖体有可能 与前mRNAs或成熟mRNAs结合的蛋白质将通过 蛋白质-RNA结合试验。

The long-term objectives of the proposed research are to understand how gene structure relates to gene expression; how the cell regulates the expression of large sets of genes to produce functional plastid (70S) and cytosolic (80S) ribosomes; and how the expression of plastid- and nuclear-encoded 70S ribosomal protein genes is coordinated in the separate genomes. A large increase in the cellular content of 70S and 80S ribosomes occurs during maize leaf cell development. The specific aims are to thoroughly characterize the ribosome content throughout maize leaves; determine the content of 80S and plastid-encoded and nuclear- encoded 70S ribosomal protein mRNAs in leaves using ribosomal protein cDNAs as hybridization probes; and to examine the rates of ribosomal protein synthesis in the leaves. Additionally, the influence of 70S ribosome content on the expression nuclear- encoded 70S ribosomal protein gene expression will be studied in mutants of maize which pre cold-sensitive for the accumlation of the 70S ribosomes. These experiments are designed to determine the mechanisms leading to the balanced accumulation of 70S ribosomal proteins. Complementary to the above studies will be the investigation of 80S and nuclear-encoded 70S ribosomal protein gene structure. cDNAs for these genes be isolated using heterologous 70S and 80S ribosomal protein cDNAs. The maize cDNAs will then be used in the above experiments and to select the genomic clones from a maize library. Several 80S and nuclear-encoded 70S ribosomal protein genes will be sequenced. Transcription start and stop sites will be identified by S1 nuclease mapping and primer extension analysis. Computer-assisted sequence analysis of these genes may reveal DNA sequences that could be involved in the coordinate regulation of the ribosomal protein genes. Protein binding activity of the genes will be examined by DNA footprint analysis. Additionally, the possibility that some ribosomal proteins bind to pre-mRNAs or mature mRNAs will be tested by protein-RNA binding assays.