p53 Binding Protein 1 (53BP1, 53-BP1, FLJ41424, MGC138366, p202, p53BP1, Tumor Protein 53 Binding Protein 1, Tumor Protein p53 Binding Protein 1, TP53BP1, Tumor Suppressor p53 Binding Protein 1) (APC)

53BP1 binds to the tumor suppressor protein p53 and has a potential role in DNA damage responses. Small interfering RNA (siRNA) directed against 53BP1 in mammalian cells to demonstrated that 53BP1 is a key transducer of the DNA damage checkpoint signal. 53BP1 was required for p53 accumulation, G2-M checkpoint arrest, and the intra-S-phase checkpoint in response to ionizing radiation. 53BP1 played a partially redundant role in phosphorylation of the downstream checkpoint effector proteins Brca1 and Chk2 but was required for the formation of Brca1 foci in a hierarchical branched pathway for the...