InterPro domain: IPR000164

This entry includes histone H3 and its variant, CENP-A (Cse4 in budding yeast, Cnp1 in fission yeast, and CID/CenH3 in fruit flies). Two primate-specific forms of H3, known as H3.X and H3.Y, are found in the brain [ 1 ].

Histone H3 is one of the five histones, along with H1/H5, H2A, H2B and H4. Two copies of each of the H2A, H2B, H3, and H4 histones ensemble to form the core of the nucleosome [ 2 ]. The nucleosome forms octameric structure that wraps DNA in a left-handed manner. H3 is a highly conserved protein of 135 amino acid residues [ 3 , 4 ]. Histones can undergo several different types of post-translational modifications that affect transcription, DNA repair, DNA replication and chromosomal stability.

Eukaryotic centromeres consists of an unique nucleosome in which CENP-A can be found [ 5 ]. Human CENP-A nucleosome forms a histone octamer containing two each of histones H2A, H2B, H4 and CENP-A. Similar to the H3-containing nucleosome, the CENP-A nucleosome wraps DNA in a left-handed orientation [ 6 , 7 ]. CENP-A nucleosomes function as a scaffold on which other kinetochore proteins assemble. CENP-A may serves as an epigenetic marker for kinetochore assembly [ 8 ]. Deposition of CENP-A to the centromere requires histone chaperone HJURP (Holliday junction recognition protein) [ 9 ].

1. Identification and characterization of two novel primate-specific histone H3 variants, H3.X and H3.Y. J. Cell Biol. 190, 777-91
2. Recognition and classification of histones using support vector machine. J. Comput. Biol. 13, 102-12
3. Phylogenetic analysis of the core histones H2A, H2B, H3, and H4. Nucleic Acids Res. 22, 174-9
4. Histone and histone gene compilation and alignment update. Nucleic Acids Res. 19 Suppl, 2173-88
5. Putting CENP-A in its place. Cell. Mol. Life Sci. 70, 387-406
6. Crystal structure of the human centromeric nucleosome containing CENP-A. Nature 476, 232-5
7. Comparison between the CENP-A and histone H3 structures in nucleosomes. Nucleus 3, 6-11
8. Kinetochore composition and its function: lessons from yeasts. FEMS Microbiol. Rev. 38, 185-200
9. Structure of a CENP-A-histone H4 heterodimer in complex with chaperone HJURP. Genes Dev. 25, 901-6