Source:http://linkedlifedata.com/resource/umls/id/C1512581
NCI: The packaging of eukaryotic DNA into nucleosomes inhibits the access of factors to DNA and results in the repression of transcription, replication, and recombination. Local modification of histones on enhancers and promoters is required to activate gene expression. The transcription factors that bind to nucleosome-free regions of DNA or to DNA within nucleosomes recruit two types of enzymatic activities that modify the surrounding chromatin architecture. Chromatin remodeling machines, such as SWI/SNF complex, alter the structure of the pronucleosome in an ATP-dependent manner, and often cause nucleosome sliding. The second type of chromatin modifying complexes recruited by transcription factors covalently modify the N-terminal tails of histones by adding or removing phosphate, methyl, or acetyl groups. Virus-induced transcription of the human interferon-beta gene illustrates one of the best-characterized examples of the mechanisms by which the information contained in the DNA is transferred to the histon