We have identified a series of proteins based on an affinity for cisplatin damaged DNA. One protein termed DRP-1 has been purified to homogeneity and was isolated as two distinct complexes. The first complex is a heterodimer of 83 and 68 kDa subunits, while the second complex is a heterotrimer of 350, 83 and 68 kDa subunits in a 1:1:1 ratio. The 83 and 68 kDa subunits in each complex are identical. The 83 kDa subunit of DRP-1 was identified as the p80 subunit of Ku autoantigen by N-terminal protein sequence and western blot analysis. The 68 kDa subunit of DRP-1 cross reacted with monoclonal antisera raised against the Ku autoantigen p70 subunit. The 350 kDa subunit was identified as Prkdc, the catalytic subunit of the human DNA-activated protein kinase, DNA-PK. DRP-1 DNA binding was assessed in mobility shift assays and results indicate that DNA binding was essentially unaffected by cisplatin-DNA adducts in the presence or absence of Prkdc. DNA-PK activity was only stimulated with undamaged DNA, despite the ability of Ku to bind to cisplatin damaged DNA. The lack of DNA-PK stimulation by cisplatin damaged DNA correlated with the extent of cisplatin-DNA adduct formation. These results are discussed with respect to the repair of cisplatin-DNA adducts and the role of DNA-PK in coordinating DNA repair processes.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology