Isolation of Ku70-binding proteins (KUBs).

DNA-dependent protein kinase (DNA-PK) plays a critical role in resealing DNA double-stand breaks by non-homologous end joining. Aside from DNA-PK, XRCC4 and DNA ligase IV, other proteins which play a role(s) in this repair pathway remain unknown; DNA-PK contains a catalytic subunit (DNA-PKcs) and a DNA binding subunit (Ku70 and ...
Ku80). We isolated Ku70-binding proteins (KUB1-KUB4) using yeast two-hybrid analyses. Sequence analyses revealed KUB1 to be apolipoprotein J (apoJ), also known as X-ray-inducible transcript 8 (XIP8), testosterone-repressed prostate message-2 (TRPM-2) and clusterin. KUB2 is Ku80. KUB3 and KUB4 are unknown, >10 kb trans-cripts. Interactions of apoJ/XIP8 or KUB3 with Ku70 were confirmed by co-immunoprecipitation analyses in MCF-7:WS8 breast cancer or IMR-90 normal lung fibroblast cells, respectively. The interaction of apoJ/XIP8 with Ku70 was confirmed by far-western analyses. Stable over-expression of full-length apoJ/XIP8 in MCF-7:WS8 caused decreased Ku70/Ku80 DNA end binding that was restored by apoJ/XIP8 monoclonal antibodies. The role of apoJ/XIP8 in ionizing radiation resistance/sensitivity is under investigation.
Mesh Terms:
Animals, Antigens, Nuclear, Base Sequence, Carrier Proteins, Cell Line, Cloning, Molecular, Clusterin, DNA Helicases, DNA Probes, DNA Repair, DNA-Activated Protein Kinase, DNA-Binding Proteins, Glycoproteins, Humans, Mice, Molecular Chaperones, Nuclear Proteins, Protein Binding, Protein-Serine-Threonine Kinases, Recombinant Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Tumor Cells, Cultured
Nucleic Acids Res.
Date: May. 15, 1999
Download Curated Data For This Publication
4940
Switch View:
  • Interactions 7