The DNA topoisomerase IIbeta binding protein 1 (TopBP1) interacts with poly (ADP-ribose) polymerase (PARP-1).

We investigated the physical association of the DNA topoisomerase IIbeta binding protein 1 (TopBP1), involved in DNA replication and repair but also in regulation of apoptosis, with poly(ADP-ribose) polymerase-1 (PARP-1). This enzyme plays a crucial role in DNA repair and interacts with many DNA replication/repair factors. It was shown that ...
the sixth BRCA1 C-terminal (BRCT) domain of TopBP1 interacts with a protein fragment of PARP-1 in vitro containing the DNA-binding and the automodification domains. More significantly, the in vivo interaction of endogenous TopBP1 and PARP-1 proteins could be shown in HeLa-S3 cells by co-immunoprecipitation. TopBP1 and PARP-1 are localized within overlapping regions in the nucleus of HeLa-S3 cells as shown by immunofluorescence. Exposure to UVB light slightly enhanced the interaction between both proteins. Furthermore, TopBP1 was detected in nuclear regions where poly(ADP-ribose) (PAR) synthesis takes place and is ADP-ribosylated by PARP-1. Finally, cellular (ADP-ribosyl)ating activity impairs binding of TopBP1 to Myc-interacting zinc finger protein-1 (Miz-1). The results indicate an influence of post-translational modifications of TopBP1 on its function during DNA repair.
Mesh Terms:
Adenosine Diphosphate Ribose, Binding Sites, Carrier Proteins, Cell Nucleus, DNA-Binding Proteins, HeLa Cells, Humans, Immunoprecipitation, Kruppel-Like Transcription Factors, Nuclear Proteins, Poly (ADP-Ribose) Polymerase-1, Poly(ADP-ribose) Polymerases, Protein Structure, Tertiary
J. Cell. Biochem.
Date: Sep. 01, 2007
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