Histone H3

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H3 histone, family 3A (H3.3A)
Symbol H3F3A
Alt. symbols H3F3
Entrez 3020
HUGO 4764
OMIM 601128
RefSeq NM_002107
UniProt Q66I33
Other data
Locus Chr. 1 q41
H3 histone, family 3B (H3.3B)
Symbol H3F3B
Entrez 3021
HUGO 4765
OMIM 601058
RefSeq NM_005324
UniProt P84243
Other data
Locus Chr. 17 q25

Histone H3 is one of the five main histone proteins involved in the structure of chromatin in eukaryotic cells.[1][2] Featuring a main globular domain and a long N-terminal tail, H3 is involved with the structure of the nucleosomes of the 'beads on a string' structure. Histone proteins are highly post-translationally modified however Histone H3 is the most extensively modified of the five histones. The term "Histone H3" alone is purposely ambiguous in that it does not distinguish between sequence variants or modification state. Histone H3 is an important protein in the emerging field of epigenetics, where its sequence variants and variable modification states are thought to play a role in the dynamic and long term regulation of genes.

Epigenetics and post-translational modifications[edit]

The N-terminal tail of histone H3 protrudes from the globular nucleosome core and can undergo several different types of post-translational modification that influence cellular processes. These modifications include the covalent attachment of methyl or acetyl groups to lysine and arginine amino acids and the phosphorylation of serine or threonine. Di- and Tri-methylation of Lysine 9 are associated with repression and heterochromatin, while mono-methylation of K4 (K4 corresponds to lysine residue at 4th position) is associated with active genes.[3][4] Acetylation of histone H3 occurs at several different lysine positions in the histone tail and is performed by a family of enzymes known as histone acetyltransferases (HATs). Acetylation of lysine14 is commonly seen in genes that are being actively transcribed into RNA.

Sequence variants[edit]

Mammalian cells have seven known sequence variants of histone H3. These are denoted as Histone H3.1, Histone H3.2, Histone H3.3, Histone H3.4 (H3T), Histone H3.5, Histone H3.X and Histone H3.Y but have highly conserved sequences differing only by a few amino acids.[5][6] Histone H3.3 has been found to play an important role in maintaining genome integrity during mammalian development.[7] Histone variants from different organisms, their classification and variant specific features can be found in "HistoneDB - with Variants" database.


Histone H3s are coded by several genes in the human genome, including:

See also[edit]

H1 H2A H2B H4


  1. ^ Bhasin M, Reinherz EL, Reche PA (2006). "Recognition and classification of histones using support vector machine". Journal of Computational Biology. 13 (1): 102–12. PMID 16472024. doi:10.1089/cmb.2006.13.102. 
  2. ^ Hartl Daniel L.; Freifelder David; Snyder Leon A. (1988). Basic Genetics. Boston: Jones and Bartlett Publishers. ISBN 0-86720-090-1. 
  3. ^ Rosenfeld JA, Wang Z, Schones DE, Zhao K, DeSalle R, Zhang MQ (March 2009). "Determination of enriched histone modifications in non-genic portions of the human genome". BMC Genomics. 10: 143. PMC 2667539Freely accessible. PMID 19335899. doi:10.1186/1471-2164-10-143. 
  4. ^ Lachner M, O'Carroll D, Rea S, Mechtler K, Jenuwein T (Mar 2001). "Methylation of histone H3 lysine 9 creates a binding site for HP1 proteins". Nature. 410 (6824): 116–20. PMID 11242053. doi:10.1038/35065132. 
  5. ^ Marzluff WF, Gongidi P, Woods KR, Jin J, Maltais LJ (Nov 2002). "The human and mouse replication-dependent histone genes". Genomics. 80 (5): 487–98. PMID 12408966. doi:10.1016/S0888-7543(02)96850-3. 
  6. ^ Hake SB, Garcia BA, Duncan EM, Kauer M, Dellaire G, Shabanowitz J, Bazett-Jones DP, Allis CD, Hunt DF (Jan 2006). "Expression patterns and post-translational modifications associated with mammalian histone H3 variants". The Journal of Biological Chemistry. 281 (1): 559–68. PMID 16267050. doi:10.1074/jbc.M509266200. 
  7. ^ Jang CW, Shibata Y, Starmer J, Yee D, Magnuson T (Jul 2015). "Histone H3.3 maintains genome integrity during mammalian development". Genes & Development. 29 (13): 1377–92. PMC 4511213Freely accessible. PMID 26159997. doi:10.1101/gad.264150.115.