Phospho-Histone H2A.X (Ser139) Monoclonal Antibody (CR55T33), eBioscience™, Invitrogen™

Description

• The CR55T33 MAb recognizes phosphorylated serine 139 of human and mouse H2AX
• H2AX is a member of the H2A histone family that complex with DNA and other histones to form the repeating nucleosome units characteristic of eukaryotic chromatin
• Nucleosomes consist of approximately 147 base pairs of DNA wrapped around an octamer of histones composed of two each of the four histone proteins: H2A, H2B, H3 and H4
• After induction of DNA damage such as double-strand breaks by irradiation, genotoxic stresses, replication errors or gene recombination, PI3K-like kinases (e.g., ataxia telangiectasia mutated (ATM), ataxia telangiectasia Rad-3-related (ATR), and DNA-dependent protein kinase (DNA-PK) are activated to phosphorylate serine 139 in H2AX
• This early phosphorylation event plays a critical role in recruiting proteins involved in DNA repair
• The MAb CR55T33 recognizes a single band of approximately 15 kDa on reduced cell lysates from Jurkat cells stimulated with etoposide
• Histone H2A.X (H2AX) is a member of the histone H2A family which is one of the four core histones making up the nucleosome core particle
• In eukaryotes, DNA double strand breaks (DSBs) have been shown to trigger the phosphorylation of serine 139 at the carboxy terminus of histone H2AX resulting in gamma-H2AX
• The phosphorylation of H2AX can be detected by Western blotting or immunofluorescence, revealing the frequency of DSBs
• The phosphatidylinositol 3-kinases have been implicated in H2AX phosphorylation, but it is unclear if ATM is the primary H2AX kinase or if other members of the family such as DNA-PK and ATR contribute in a similar manner
• Structurally, H2A.x contains 143 amino acid residues
• Histone H2A.X is considered a basal histone, being synthesized in G1 as well as in S-phase, and its mRNA contains polyA addition motifs and a polyA tail along with the conserved stem-loop and U7 binding sequences involved in the processing and stability of replication type histone mRNAs
• There are two forms of Histone H2A.X mRNA, one about 1600 bases long and contains polyA; the other about 575 bases long, lacking polyA
• The short form behaves as a replication type histone mRNA, while the longer behaves as a basal type histone mRNA
• Histone H2A.X maps to the 11q23.2-q23.3 region of the human chromosome
• Histone H2A.x contributes to histone-formation and therefore the structure of DNA
• Histone H2A variant H2A.x specifically regulates the interaction of MDC1 (mediator of DNA damage checkpoint protein 1), a DNA repair protein to the sites of DNA damage.