Histone H2B is one of the 5 main histone proteins involved in the structure of chromatin in eukaryotic cells. Featuring a main globular domain and long N-terminal and C-terminal tails, H2B is involved with the structure of the nucleosomes. Histone H2B is a structural protein that helps organize eukaryotic DNA. It plays an important role in the biology of the nucleus where it is involved in the packaging and maintaining of chromosomes, regulation of transcription, and replication and repair of DNA. Histone H2B helps regulate chromatin structure and function through post-translational modifications and specialized histone variants.