H2A Histone Family, Member X (H2AFX)

H2AX is a member of the histone H2A family, 1 of 5 families of histone proteins involved in nucleosomal organization of chromatin.the gene encodes a 142-amino acid protein having a unique C-terminal sequence, QASQEY, which has been conserved from lower eukaryotes.

Nijmegen breakage syndrome protein (NBS1) and phosphorylated H2AX (gamma-H2AX), which associate with irradiation-induced DNA double-strand breaks (DSBs), are also found at sites of V(D)J (variable, diversity, joining) recombination-induced DSBs. In developing thymocytes, NBS1 and gamma-H2AX form nuclear foci that colocalize with the T-cell receptor-alpha (TCRA) locus in response to recombination-activating gene-1 (RAG1) protein-mediated V(D)J cleavage.