Preobrazhenskaia O V, Karpov V L, Nagorskaia T V, Mirzabekov A D
Mol Biol (Mosk). 1984 Jan-Feb;18(1):8-20.
A method of attaching proteins to specific sites of DNA has been developed. The proteins are fixed on DNA directly in the cell nucleus by covalent bonding. DNA's associated with different proteins are divided into several diagonals by the two-dimensional gel-electrophoresis. The nucleotide sequences linked to proteins are then identified by hybridizing them with cloned probes of DNA. This method was used for Drosophila cells to determine the presence of histones in the transcribed site of the hsp-22 gene, activated by heat shock, and also in the neighboring active gene and non-transcribed insertion in ribosomal RNA genes. It was found that moderate transcription removed H1 and part of core histones, whereas intensive transcription removed all histones from the structural region of the genes. The substitution of core histones by RNA-polymerase within the transcribed region seems to cause the removal of first H1 and then core histones (depending on the intensity of the process) from prolonged regions of chromatin, which leads to a 25 nm fibrilla being decondensed to a 10 nm thread and, finally, to a completely linearized histone-free DNA.
一种将蛋白质附着于DNA特定位点的方法已被开发出来。这些蛋白质通过共价键直接在细胞核内固定于DNA上。与不同蛋白质相关联的DNA通过二维凝胶电泳被分成若干对角线。然后通过将与蛋白质相连的核苷酸序列与DNA克隆探针杂交来鉴定它们。该方法用于果蝇细胞，以确定热休克激活的hsp - 22基因转录位点中组蛋白的存在情况，以及相邻的活性基因和核糖体RNA基因中的非转录插入片段中的组蛋白情况。研究发现，适度转录会去除H1和部分核心组蛋白，而高强度转录会从基因的结构区域去除所有组蛋白。转录区域内RNA聚合酶对核心组蛋白的替代似乎会导致H1首先从染色质的延长区域被去除，然后核心组蛋白（取决于该过程的强度）也被去除，这会导致25纳米的纤维状结构解聚为10纳米的细丝，最终形成完全线性化的无组蛋白DNA。
