- Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.
Definition from: MeSH via Unified Medical Language System at the National Library of Medicine
- A histone is a protein that provides structural support to a chromosome. In order for very long DNA molecules to fit into the cell nucleus, they wrap around complexes of histone proteins, giving the chromosome a more compact shape. Some variants of histones are associated with the regulation of gene expression.
Definition from: Talking Glossary of Genetic Terms from the National Human Genome Research Institute
Related discussion in the Handbook
See also Understanding Medical Terminology.