Points of sequence variation and modifications on human H2B isoforms. (A) Modification sites on the H2B N-terminal tail and C-terminal tail. Sites of sequence variation are in bold. (B) Sequence alignment of H2B isoforms. Points of sequence variation are highlighted in purple. Somatic isoforms are listed in red, and testis-specific variants are in blue. Variants H2BFM and H2BFWT differ significantly from other H2B isoforms across their entire sequences. Me = methylation, Ac = acetylation, Ph = phosphorylation, G = glycosylation, Ub = ubiquitination.