p140/c-Abl that binds DNA is preferentially phosphorylated at tyrosine residues.
EP is a DNA element found in the enhancer and promoter regions of several cellular and viral genes. Previously, we have identified the DNA binding p140/c-Abl protein that specifically recognizes this element. Here we show that phosphorylation is essential for the p140/c-Abl DNA binding activity and for the formation of DNA-protein complexes. Furthermore, by 32P labeling of cells and protein purification, we demonstrate that in vivo the EP-DNA-associated p140/c-Abl is a tyrosine phosphoprotein. By employing two different c-Abl antibodies, we demonstrate the existence of two distinct c-Abl populations in cellular extracts. p140/c-Abl is quantitatively the minor population, is heavily phosphorylated at both serine and tyrosine residues, and is active in autophosphorylation reactions.
Dikstein
R
R
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Agami
R
R
Heffetz
D
D
Shaul
Y
Y
D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D006367:HeLa Cells; D006801:Humans; D007158:Immunologic Techniques; D019000:Phosphotyrosine / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism*
D004268:DNA-Binding Proteins; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D016315:Proto-Oncogene Proteins c-abl