H2AFX

H2AFX, also known as H2AX, is a histone protein found in eukaryotes. Histones are proteins that package and organize DNA into structures called nucleosomes, which form chromatin. H2AFX is a variant of the histone H2A protein, distinguished by a unique C-terminal tail sequence. This variant plays a crucial role in DNA damage response and repair.

Upon the induction of DNA double-strand breaks (DSBs), a DNA repair mechanism is triggered. A key event in this process is the phosphorylation of H2AFX at a specific serine residue (serine 139) within its C-terminal tail. This phosphorylated form is known as gamma-H2AFX. The recruitment of various DNA repair proteins to the site of damage is facilitated by the presence of gamma-H2AFX. These proteins are essential for recognizing, signaling, and ultimately repairing the broken DNA.

The formation of gamma-H2AFX foci, which are visible under microscopy, serves as a marker for DNA DSBs. The extent and duration of gamma-H2AFX formation can indicate the severity of DNA damage and the efficiency of the repair process. H2AFX is conserved across many species, highlighting its fundamental importance in maintaining genomic stability. Its role extends beyond simple DNA repair, as it is also implicated in processes such as chromatin remodeling, gene regulation, and meiotic recombination.