Glossary Term
Histone
Definition
Major protein component of chromatin. Highly conserved basic proteins, originally classified into classes based on the relative amounts of arginine and lysine in each protein. The various classes are now termed H1, H2A, H2B, H3, and H4. In chromatin, they are found in an octamer, containing two each of H2A, H2B, H3, and H4, complexed with DNA in nucleosomes. The histones in the octamer complex are also known as the core histones. The H1 class of histones, termed the linker histones, is loosely associated with the nucleosome.
Extended Notes
Source: National Cancer Institute, NCI Thesaurus 26.09d, C16687. NCI definition, reproduced without modification under CC BY 4.0. Source identity and definition checked automatically on 2026-10-20. No individual clinical interpretation or human reviewer is asserted.