English: (a) The flexible amino- terminal tail of each histone extends from the surface of the histone octamer. (b) In 30-nm fibers, the histone tails of one nucleosome interact with the histones and DNA of adjacent nucleosomes. In some chromatin, histone tails also interact with non-histone proteins (green) that help package the DNA. Linker histones (histone H1, red) also contribute to chromatin formation. Acetylation of histone tails alters their interaction with other nucleosomes and non-histone proteins, generally resulting in a more open chromatin structure.