A ubiquitous nuclear protein stimulates the DNA-binding activity of fos and jun indirectly.
The protooncogenes c-fos and c-jun encode nuclear proteins (fos and jun, respectively) that function cooperatively as a heterodimeric protein complex in the regulation of gene transcription. These proteins dimerize via a structural motif known as the leucine zipper and bind to activator protein-1 sites via a conserved domain that is rich in basic amino acids. Previously, we demonstrated that while fos and jun polypeptides expressed in Escherichia coli dimerize efficiently, they exhibit only a low level of DNA-binding activity. Here we show that the DNA-binding activity of fos-jun heterodimers and jun-jun homodimers is stimulated dramatically by a ubiquitous nuclear protein. This protein does not appear to participate in the DNA-protein complex, and it does not affect the specificity of the interaction with DNA. These results suggest that a nuclear protein regulates the DNA-binding activity of fos and jun indirectly.
Abate
C
C
Department of Molecular Oncology and Virology, Roche Research Center, Nutley, New Jersey 07110.
Luk
D
D
Curran
T
T
D000595:Amino Acid Sequence; D001483:Base Sequence; D001685:Biological Factors / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D001685:Biological Factors; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors