Histone H2B is a protein encoded by the HIST1H2BA gene which is approximately 14,1 kDa. Histone H2B is localised to the nucleus. It is involved in DNA double-strand break repair, cellular senescence, chromosome maintenance and mitotic cell cycle. Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. Two molecules of each of the four core histones (H2A, H2B, H3, and H4) form an octamer, around which approximately 146 bp of DNA is wrapped in repeating units. Histone H2B is mainly expressed in testis, it is also found in some fat cells. STJ97064 was affinity-purified from rabbit antiserum by affinity-chromatography using specific immunogen. This antibody detects endogenous Histone H2B protein.