ATR(redirected from MEC1, mitosis entry checkpoint 1, homolog)
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ATRA gene on chromosome 3q22-q24 that encodes a protein belonging to the PI3/PI4-kinase family, which is closely related to ATM, the protein kinase encoded by the gene mutated in ataxia telangiectasia. ATR is similar to the cell cycle checkpoint gene required for cell cycle arrest and DNA damage repair in response to DNA damage; it phosphorylates checkpoint kinase CHK1 and checkpoint proteins RAD17 and RAD9, as well as tumour suppressor protein BRCA1.
ATR mutations cause Seckel syndrome.