The product of a novel growth factor activated gene, fos B, interacts with JUN proteins enhancing their DNA binding activity.
We have identified a gene, fos B, encoding a nuclear protein of 338 amino acids presenting a 70% homology with c-fos, whose expression is activated during G0/G1 transition. Growth factor stimulation of quiescent cells leads to a rapid and transient accumulation of fos B mRNA, with kinetics similar to those of c-fos. The induction of fos B mRNA levels is in part due to a dramatic increase in the transcription of the gene. The half-life of fos B mRNA is in the order of 10-15 min. Both transcriptional activation and mRNA stability are substantially increased in the presence of protein synthesis inhibitors. Immunoprecipitation studies showed that fos B as c-fos protein, forms a complex in vitro with c-jun and jun B proteins in the absence of a target binding sequence. Gel retardation assays demonstrated that fos B protein positively influences the binding of c-jun and jun B proteins to an AP-1 binding consensus sequence, suggesting that fos B protein plays a role in control of gene expression.
Zerial
M
M
European Molecular Biology Laboratory, Heidelberg, FRG.
Toschi
L
L
Ryseck
R P
RP
Schuermann
M
M
Müller
R
R
Bravo
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D051379:Mice; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011519:Proto-Oncogenes; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D004247:DNA