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当RNA聚合酶Ⅱ(RNAPⅡ)离开启动子开始转录延伸时,会遇到包括紧密包装形成染色质的核小体在内的多种障碍,细胞内存在多种因子可协助RNAPⅡ克服这些障碍,保证转录的顺利进行。遗传和生化研究已经分离和鉴定了一些在此过程中起作用的延伸因子(elongation factor),现依据作用方式和效果对目前发现的主要延伸因子的研究进展进行了分类综述。 相似文献
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Philippe Lefran?ois Raymond K. Auerbach Christopher M. Yellman G. Shirleen Roeder Michael Snyder 《PLoS genetics》2013,9(1)
Accurate chromosome segregation requires centromeres (CENs), the DNA sequences where kinetochores form, to attach chromosomes to microtubules. In contrast to most eukaryotes, which have broad centromeres, Saccharomyces cerevisiae possesses sequence-defined point CENs. Chromatin immunoprecipitation followed by sequencing (ChIP–Seq) reveals colocalization of four kinetochore proteins at novel, discrete, non-centromeric regions, especially when levels of the centromeric histone H3 variant, Cse4 (a.k.a. CENP-A or CenH3), are elevated. These regions of overlapping protein binding enhance the segregation of plasmids and chromosomes and have thus been termed Centromere-Like Regions (CLRs). CLRs form in close proximity to S. cerevisiae CENs and share characteristics typical of both point and regional CENs. CLR sequences are conserved among related budding yeasts. Many genomic features characteristic of CLRs are also associated with these conserved homologous sequences from closely related budding yeasts. These studies provide general and important insights into the origin and evolution of centromeres. 相似文献
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