In response to genomic stress, the ATR interacting protein (ATRIP) binds and is phosphorylated by the DNA damage-and checkpoint-activated kinase ATR (ataxia-telangiectasia mutated and rad3-related). Both ATR and ATRIP are integral for checkpoint signaling and are critical in the DNA repair response (1-3). Direct interaction between ATRIP and replication protein A (RPA) at RPA-coated, single-stranded DNA results in the recruitment of phosphorylated ATR/ATRIP to stalled replication forks and sites of DNA damage (3). ATR/ATRIP coordinate DNA repair and cell cycle progression in conjunction with key regulatory proteins, such as Rad17 and the 9-1-1 complex (4). ATR associated with ATRIP can also be stimulated by topoisomerase II binding protein (TOPBP1), suggesting that ATRIP may regulate both ATR localization and activity (5).Cyclin dependent kinase 2 (CDK2) may participate in the regulation of DNA damage response and cell cycle control through phosphorylation of ATRIP at Ser224 (6). |