Description
Tumor Protein p53-Binding Protein 1, also called 53BP1, is a protein that in humans is encoded by the TP53BP1 gene. Iwabuchi et al.(1998) mapped the gene to 15q15-q21 by FISH. Iwabuchi et al.(1994) showed that TP53BP1 binds to the conformationally sensitive central domain of wildtype p53 but not to mutant p53 in vitro. Immunoblot analysis by Iwabuchi et al.(1998) showed that expression of TP53BP1 or TP53BP2 enhances the transactivation function of p53 and induces the expression of p21(CDKN1A). Wang et al.(2002) used small interfering RNA directed against the protein in mammalian cells to demonstrate that TP53BP1 is a key transducer of the DNA damage checkpoint signal. It was required for p53 accumulation, G2/M checkpoint arrest, and the intra-S-phase checkpoint in response to ionizing radiation