H2AXfokukset
H2AX foci, also known as γ‑H2AX foci, are focal accumulations of a modified histone protein that form at sites of DNA double‑strand breaks. They appear when the serine 139 residue of the histone variant H2AX is phosphorylated by at least one member of the PIKK family of kinases, principally ATM, ATR, or DNA‑PKcs. Phosphorylated H2AX, termed γ‑H2AX, undergoes a rapid, large‑scale chromatin response, creating a nucleoprotein platform that recruits additional DNA‑damage response (DDR) factors such as MDC1, 53BP1, and BRCA1. This recruitment is critical for the amplification of the damage signal, the recruitment of repair proteins, and the coordination of repair pathway choice.
The appearance of H2AX foci is typically detected by immunofluorescent microscopy using antibodies directed against the
Research established the γ‑H2AX focus assay in the late 1990s, and since then it has become a
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