Catalytic activity:ATP + a protein = ADP + a phosphoprotein. ,Disease:Defects in ATM are the cause of ataxia telangiectasia (AT) [MIM:208900]; also known as Louis-Bar syndrome , which includes four complementation groups: A , C , D and E. This rare recessive disorder is characterized by progressive cerebellar ataxia , dilation of the blood vessels in the conjunctiva and eyeballs , immunodeficiency , growth retardation and sexual immaturity. AT patients have a strong predisposition to cancer; about 30% of patients develop tumors , particularly lymphomas and leukemias. Cells from affected individuals are highly sensitive to damage by ionizing radiation and resistant to inhibition of DNA synthesis following irradiation. ,Disease:Defects in ATM contribute to B-cell chronic lymphocytic leukemia (BCLL) . BCLL is the commonest form of leukemia in the elderly. It is characterized by the accumulation of mature CD5+ B lymphocytes , lymphadenopathy , immunodeficiency and bone marrow failure. ,Disease:Defects in ATM contribute to B-cell non-Hodgkin lymphomas (BNHL) , including mantle cell lymphoma (MCL) . ,Disease:Defects in ATM contribute to T-cell acute lymphoblastic leukemia (TALL) and T-prolymphocytic leukemia (TPLL) . TPLL is characterized by a high white blood cell count , with a predominance of prolymphocytes , marked splenomegaly , lymphadenopathy , skin lesions and serous effusion. The clinical course is highly aggressive , with poor response to chemotherapy and short survival time. TPLL occurs both in adults as a sporadic disease and in younger AT patients. ,Domain:The FATC domain is required for interaction with HTATIP. ,enzyme regulation:Inhibited by wortmannin. ,Function:Serine/threonine protein kinase which activates checkpoint signaling upon double strand breaks (DSBs) , apoptosis and genotoxic stresses such as ionizing ultraviolet A light (UVA) , thereby acting as a DNA damage sensor. Recognizes the substrate consensus sequence [ST]-Q. Phosphorylates 'Ser-139' of histone variant H2AX/H2AFX at double strand breaks (DSBs) , thereby regulating DNA damage response mechanism. Also involved in signal transduction and cell cycle control. May function as a tumor suppressor. Necessary for activation of ABL1 and SAPK. Phosphorylates p53/TP53 , FANCD2 , NFKBIA , BRCA1 , CTIP , nibrin (NBN) , TERF1 , RAD9 and DCLRE1C. May play a role in vesicle and/or protein transport. Could play a role in T-cell development , gonad and neurological function. ,induction:By ionizing radiation. ,online information:Ataxia telangiectasia mutated entry ,PTM:Acetylation , on DNA damage , is required for activation of the kinase activity , dimer-monomer transition , and subsequent autophosphorylation on Ser-1981. Acetylated in vitro by HTATIP/TIP60. ,PTM:Phosphorylated by NUAK1/ARK5. Autophosphorylation on Ser-367 , Ser-1983 , Ser-1981 correlates with DNA damage-mediated activation of the kinase. ,similarity:Belongs to the PI3/PI4-kinase family. ATM subfamily. ,similarity:Contains 1 FAT domain. ,similarity:Contains 1 FATC domain. ,similarity:Contains 1 PI3K/PI4K domain. ,subcellular location:Primarily nuclear. Found also in endocytic vesicles in association with beta-adaptin. ,subunit:Dimers or tetramers in inactive state. On DNA damage , autophosphorylation dissociates ATM into monomers rendering them catalytically active. Binds DNA ends , p53/TP53 , ABL1 , BRCA1 , NBN/nibrin and TERF1. Part of the BRCA1-associated genome surveillance complex (BASC) , which contains BRCA1 , MSH2 , MSH6 , MLH1 , ATM , BLM , PMS2 and the RAD50-MRE11-NBN protein complex. This association could be a dynamic process changing throughout the cell cycle and within subnuclear domains. DNA damage promotes association with RAD17. Interacts with EEF1E1; the interaction , induced on DNA damage , upregulates TP53. Interacts with DCLRE1C , MYST1 , HTATIP , OBFC2B , ATMIN and CEP164. Interacts with the beta-adaptin complex subunits , AP2B1 AND AP3B2; the interaction occurs in cytoplasmic vesicles. ,tissue specificity:Found in pancreas , kidney , skeletal muscle , liver , lung , placenta , brain , heart , spleen , thymus , testis , ovary , small intestine , colon and leukocytes. ,
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