H2A

Histones are nuclear proteins essential for the storage and organization of genomic DNA as chromatin. Chromatin consists of DNA wrapped tightly around histone oligomers to form nucleosomes. In addition to compacting the genome, histones also regulate the accessibility of the DNA to the transcription and replication machinery to influence gene expression and mitosis.

Histones are the main protein component of chromatin and are essential for the storage and compaction of the genome. DNA wraps around histone oligomers to make up nucleosomes, the individual subunits of chromatin. By altering the accessibility of the genome, chromatin structure is important for regulating various cellular processes including replication, transcription, and DNA repair. Typically chromatin structure is influenced by post-translational modification of histone proteins at lysine and arginine residues.

Eukaryotic chromosomes are formed through the highly organized and structural wrapping of DNA genetic material around histone proteins into the classic "bead on a string" globular structure of nucleosomes. The histone family consists of five family members - histone H1, H2A, H2B, H3, and H4.