Histone octamer
Histone octamer
A histone octamer is a protein complex that plays a crucial role in the structure and function of chromatin in eukaryotic cells. It is composed of eight histone proteins, which are organized into a core particle around which DNA is wrapped. This structure is fundamental to the formation of nucleosomes, the basic unit of chromatin.
Composition[edit | edit source]
The histone octamer consists of two copies each of four core histone proteins: H2A, H2B, H3, and H4. These histones are highly conserved across different species, reflecting their essential role in chromatin structure and function.
Structure[edit | edit source]
The histone octamer forms a disc-shaped structure around which approximately 147 base pairs of DNA are wrapped in 1.65 left-handed superhelical turns. This DNA-histone complex is known as a nucleosome. The nucleosome is connected to adjacent nucleosomes by a stretch of linker DNA, which can vary in length.
Function[edit | edit source]
The primary function of the histone octamer is to package DNA into a more compact, dense shape, which allows for efficient storage of genetic information within the cell nucleus. This packaging also plays a critical role in regulating gene expression, as the accessibility of DNA to transcription factors and other regulatory proteins is influenced by the positioning and modification of nucleosomes.
Histone Modifications[edit | edit source]
Histone proteins within the octamer can undergo various post-translational modifications, such as methylation, acetylation, phosphorylation, and ubiquitination. These modifications can alter the interaction between histones and DNA, as well as the interaction between nucleosomes, thereby influencing chromatin structure and gene expression.
Role in Disease[edit | edit source]
Abnormalities in histone modifications and chromatin structure can lead to various diseases, including cancer, neurodegenerative disorders, and developmental disorders. Understanding the role of the histone octamer in these processes is a significant area of research in epigenetics.
See also[edit | edit source]
References[edit | edit source]
External links[edit | edit source]
 | This cell biology article is a stub. You can help WikiMD by expanding it. |
Navigation: Wellness - Encyclopedia - Health topics - Disease Index - Drugs - World Directory - Gray's Anatomy - Keto diet - Recipes
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
WikiMD is not a substitute for professional medical advice. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.Contributors: Prab R. Tumpati, MD
