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.

The protein is named for the disorder Ataxia telangiectasia caused by mutations of ATM.

