Histone H2A Proteins and Enzymes

Changes in chromatin structure play a large role in the regulation of transcription in eukaryotes (1). The nucleosome is the primary building block of chromatin, and is made up of four core histone proteins (H2A, H2B, H3 and H4) (2). It has been shown that DNA damage induces monoubiquitylation of histone H2A in the vicinity of DNA lesions. Ultraviolet -induced monoubiquitylation of H2A is dependent on functional nucleotide excision repair. It occurs after incision of the damaged strand and forms part of the cellular response to UV damage and suggests a role of this modification in DNA repair-induced chromatin remodeling (3).