Article: article from journal or magazin.
Ethidium bromide provides a simple tool for identifying genuine DNA-independent protein associations.
Proceedings of the National Academy of Sciences of the United States of America
DNA-dependent and DNA-independent associations of DNA-binding proteins are important in transcriptional regulation. The analysis of DNA-independent associations frequently relies on assaying protein interaction in the absence of target DNA sequences. We have found that contaminating DNA in protein preparations can stabilize DNA-dependent associations that may appear DNA-independent. Three cellular proteins of 70, 85, and 110 kDa coimmunoprecipitated with the octamer motif-binding protein Oct-2 because of the presence of contaminating DNA in the cell extracts. In addition, heterodimer formation between Oct-1 (or Oct-2) and Pit-1 during protein-affinity chromatography was stabilized by the contaminating DNA. In both instances, these DNA-dependent protein associations were selectively inhibited by ethidium bromide in the precipitation reaction without any evident effect on DNA-independent protein associations. Thus, ethidium bromide may serve as a simple and general indicator of DNA-dependent and DNA-independent protein associations.
Animals, Base Sequence, Chromatography, Affinity, DNA, DNA-Binding Proteins, Ethidium, Glutathione Transferase, Host Cell Factor C1, Immunoglobulin Heavy Chains, Indicators and Reagents, Micrococcal Nuclease, Molecular Sequence Data, Molecular Weight, Octamer Transcription Factor-1, Oligodeoxyribonucleotides, Promoter Regions, Genetic, Protein Binding, Recombinant Fusion Proteins, Ribonucleases, Transcription Factor Pit-1, Transcription Factors, Transfection
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