Ataxia telangiectasia and Rad3 related
（重定向自MEC1）
Serine/threonine-protein kinase ATR also known as ataxia telangiectasia and Rad3-related protein (ATR) or FRAP-related protein 1 (FRP1) is an enzyme that, in humans, is encoded by the ATR gene. ATR belongs to the phosphatidylinositol 3-kinase-related kinase protein family.