真核细胞的染色质是由DNA、蛋白质(组蛋白与非组蛋白)和RNA组成,其中DNA和组蛋白是主要成分。组蛋白有H_1、H_2A、H_2B、H_3和H_4等五种不同的分子。一个连续的DNA双螺旋分子缠绕在组蛋白上形成许多相似的甚本结构,称为核体(Nucleosome)。每个核体是由核心颗粒(core particle)和连接体(linker)两部分组成。所谓核心颗粒是由组蛋白H_2A、H_2B、H_3和H_4各两个分子构成的八聚体,外面缠绕1 3/4圈DNA(146bp)链而构成。连接体连接在两个核心颗粒之间,为一段60bp的DNA链并结合一分子组蛋白H_1。近年来,真核细胞基因表达及其调控的研究都集中 Eukaryotic chromatin is composed of DNA, proteins (histones and non-histones) and RNA, of which DNA and histones are the major components. Histones have H_1, H_2A, H_2B, H_3 and H_4 other five different molecules. A continuous DNA double helix molecule wraps around the histone to form many similar, very basic structures called nucleosomes. Each core is composed of core particles and linkers. The so-called core particle is composed of two molecules of histone H_2A, H_2B, H_3 and H_4 octamer, the outer wound around 1 3/4 turn DNA (146bp) chain and the composition. The linker is attached between two core particles and is a 60 bp DNA strand that binds to a molecule of histone H_1. In recent years, the research of eukaryotic gene expression and regulation has been focused