Variant histone H2A which replaces conventional H2A in a subset of nucleosomes. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. The presence of macro-H2A enhances the interaction of the histone octamer with the nucleosomal DNA and may repress the ability of the nucleosome to be remodelled. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. Present in liver (at protein level). Present in immature erythrocytes (at protein level). Monoubiquitinated at either Lys-116 or Lys-117. ADP-ribosylated.