Anti-Histone H2A.x

Histones are major chromatin proteins that wrap DNA to form nucleosome particles. Each nucleosome core particle consists of approximately 146 bp DNA wrapped by an octamer containing 2 molecules each of histones H2A, H2B, H3, and H4. Histone H1 sits on the linker DNA between nucleosomes. Their major function is to compact long DNA strands inside the nucleus and chromatin regulation. Histone H2A X is a 15 kDa variant of Histone H2. Histone H2A X is also required for the repair of double-stranded DNA breaks particularly when modified by C-terminal phosphorylation on Ser-140. Histone H2A X is expressed in all eukaryotic cells. Protein function: 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. Required for checkpoint-mediated arrest of cell cycle progression in response to low doses of ionizing radiation and for efficient repair of DNA double strand breaks (DSBs) specifically when modified by C- terminal phosphorylation. [The UniProt Consortium]