Ataxia telangiectasia mutated

Ataxia telangiectasia mutated (ATM) is a serine/threonine-specific protein kinase  that is recruited and activated by DNA double-strand breaks. It phosphorylates several key proteins that initiate activation of the DNA damage checkpoint, leading to cell cycle arrest, DNA repair or apoptosis. Several of these targets, including p53, CHK2, BRCA1, and H2AX are tumor suppressors.
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