Phosphorylation-dependent binding of a 138-kDa myc intron factor to a regulatory element in the first intron of the c-myc gene.
A 138-kDa nuclear protein was identified from HeLa cell extracts as a factor which binds to a previously described 20-base pair cis element located in the intron I of the c-myc gene. This myc intron factor (MIF) binds to the wild type c-myc sequence but does not bind under similar conditions to c-myc from Burkitt's lymphoma which contain point mutations in this binding region. We have demonstrated that the 138-kDa MIF is a phosphoprotein and that treatment of the purified MIF with potato acid phosphatase abolished binding to its 20-base pair c-myc recognition sequence; binding activity was protected by inclusion of phosphatase inhibitors. These results suggest that phosphorylation is required for the specific DNA-MIF interaction in vitro and that the phosphorylation state of MIF may be an important factor in controlling c-myc expression in vivo.
Medicine Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
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Zajac-Kaye
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Levens
D000135:Acid Phosphatase / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000032:analysis; D004247:DNA / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015345:Oligonucleotide Probes; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc; D012045:Regulatory Sequences, Nucleic Acid
D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D004247:DNA; D000135:Acid Phosphatase