H2AFX

• OMIM: 601 772
• UniProt: P16104

Histone H2AX is a protein from the group of the histones, which occurs in the nucleus of all eukaryotes. It stabilizes the genetic information (DNA) and, together with the DNA molecules nucleosomes and other proteins with chromatin complexes. In addition, H2AX has several responsibilities in DNA repair, maintenance of chromosomes and the cell cycle. H2AX also has medicinal importance as a laboratory value for DNA damage.

Localization

It is a variant of histone H2A and is thus an essential component of chromatin. In eukaryotic cells, the DNA wrapped around a histone octamer composed of histones H2A, H2B, H3 and H4. In about 20% of all histone octamers H2A is replaced by H2AX.

Function

DNA repair

In response to, for example, a DNA double strand break H2AX phosphorylated on serine 139, is defined as the phosphorylated form of H2AX as gamma H2AX (abbreviated gH2AX or yH2AX ). Responsible for the phosphorylation of kinases are out of the PI3 kinases (ATM, ATR and DNA -PKcs ) family. gH2AX is formed in a range of about 1-2 Mega base pairs of the double-strand break around and is therefore visible by immunofluorescent staining as in the microscope focus. The formation of gH2AX occurs when replication forks collapse even without the action of exogenous noxious agents such as ionizing radiation during V (D) J recombination or during replication of DNA. Gamma - H2AX has established itself as a sensitive detection of DNA double -strand breaks in science, especially in radiation biology. The biological function of gH2AX is not yet fully understood. Studies with cells lacking H2AX showed that the repair of radiation-induced DNA double-strand breaks is limited.

Interactions with other proteins

H2AX interacts with MDC1, among other things, Nibrin, TP53BP1, BRCA1 and BARD1.