hnRNP-U is a specific DNA-dependent protein kinase substrate phosphorylated in response to DNA double-strand breaks.
Cellular responses to DNA damage are orchestrated by the large phosphoinositol-3-kinase related kinases ATM, ATR and DNA-PK. We have developed a cell-free system to dissect the biochemical mechanisms of these kinases. Using this system, we identify heterogeneous nuclear ribonucleoprotein U (hnRNP-U), also termed scaffold attachment factor A (SAF-A), as a specific substrate for DNA-PK. We show that hnRNP-U is phosphorylated at Ser59 by DNA-PK in vitro and in cells in response to DNA double-strand breaks. Phosphorylation of hnRNP-U suggests novel functions for DNA-PK in the response to DNA damage.
Berglund
Fredrik M
FM
Biomedical Research Institute, College of Medicine, Dentistry and Nursing, University of Dundee, Level 5, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, UK.
Clarke
Paul R
PR
D000595:Amino Acid Sequence; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002474:Cell-Free System / Q000201:enzymology; D000071877:Checkpoint Kinase 1; D053903:DNA Breaks, Double-Stranded; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D034722:Heterogeneous-Nuclear Ribonucleoprotein U / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011067:Poly dA-dT / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D034722:Heterogeneous-Nuclear Ribonucleoprotein U; D025521:Tumor Suppressor Proteins; D011067:Poly dA-dT; D012694:Serine; D011494:Protein Kinases; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D000071877:Checkpoint Kinase 1; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases