DNA-dependent protein kinase interacts with antigen receptor response element binding proteins NF90 and NF45.
The DNA-dependent protein kinase (DNA-PK) is composed of a large catalytic subunit of approximately 470 kDa (DNA-PKcs) and the DNA-binding protein, Ku. Absence of DNA-PK activity confers sensitivity to x-rays and defects in both DNA double-strand break repair and V(D)J recombination. However the precise function of DNA-PK in DNA double-strand ... break repair is not known. Here we show, using electrophoretic mobility shift assays, that polypeptides in a fraction purified from human cells interact with DNA-PK and stabilize the formation of a complex containing DNA-PKcs-Ku and DNA. Five polypeptides in this fraction have been identified by amino-terminal sequence analysis and/or immunoblotting. These proteins are NF90 and NF45, which are the 90- and 45-kDa subunits of a protein known to bind specifically to the antigen receptor response element of the interleukin 2 promoter, and the alpha, beta, and gamma subunits of eukaryotic translation initiation factor eIF-2. We also show that NF90, NF45, and eIF-2 beta are substrates for DNA-PK in vitro. In addition, recombinant NF90 promotes formation of a complex between DNA-PKcs, Ku, and DNA, and antibodies to recombinant NF90 or recombinant NF45 immunoprecipitate DNA-PKcs in vitro. Together, our data suggest that NF90, in complex with NF45, interacts with DNA-PKcs and Ku on DNA and that NF90 and NF45 may be important for the function of DNA-PK.
Mesh Terms:
Antigens, Nuclear, Autoantigens, DNA, DNA Helicases, DNA-Activated Protein Kinase, DNA-Binding Proteins, Eukaryotic Initiation Factor-2, Humans, Interleukin-2, Macromolecular Substances, NFATC Transcription Factors, Nuclear Factor 45 Protein, Nuclear Factor 90 Proteins, Nuclear Proteins, Phosphoproteins, Phosphorylation, Promoter Regions, Genetic, Protein-Serine-Threonine Kinases, Transcription Factors
Antigens, Nuclear, Autoantigens, DNA, DNA Helicases, DNA-Activated Protein Kinase, DNA-Binding Proteins, Eukaryotic Initiation Factor-2, Humans, Interleukin-2, Macromolecular Substances, NFATC Transcription Factors, Nuclear Factor 45 Protein, Nuclear Factor 90 Proteins, Nuclear Proteins, Phosphoproteins, Phosphorylation, Promoter Regions, Genetic, Protein-Serine-Threonine Kinases, Transcription Factors
J. Biol. Chem.
Date: Jan. 23, 1998
PubMed ID: 9442054
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