H3

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, the main protein component of chromatin, are essential for storing and organizing the genome in a compact yet accessible manner. DNA wraps tightly around histone oligomers to form nucleosomes which can store unused portions of DNA and regulate accessibility to the replication or transcription machinery. By affecting chromatin structure histones and their modifying enzymes make up a complex network with important regulatory roles in DNA replication, mitosis, and gene expression.

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.