Phosphorylation of BRCA1 at multiple sites by ATM ATM mediated phosphorylation of BRCA1 at Ser 1189, Ser 1542 and Ser 1524 (Cortez et al., 1999) is regulated by MDC1 (Lou et al., 2003). BRCA1 plays an important role in the response to double-strand breaks, participating in genome surveillance, DNA repair, and cell cycle checkpoint arrests. BRCA1 is required for ATM-dependent phosphorylation of NBS1 following exposure to ionizing radiation (Foray et al., 2003). BRCA1 also interacts with the MRE11-RAD50-NBS1 complex which has been implicated early in HRR during resection of the double-strand break. Authored: Matthews, L, 2003-11-18 00:00:00 Pubmed10550055 Pubmed12773400 Reactome Database ID Release 4375239 Reactome, http://www.reactome.org ReactomeREACT_937 has a Stoichiometric coefficient of 3