title: c-Jun dimerizes with itself and with c-Fos, forming complexes of different DNA binding affinities.
abstract: The c-Jun and c-fos proto-oncogenes encode proteins that form a complex which regulates transcription from promoters containing AP-1 activation elements. c-Jun has specific DNA binding activity, while c-Fos has homology to the putative DNA binding domain of c-Jun. Following in vitro translation, c-Jun binds as a homodimer to the AP-1 DNA site, while c-Fos fails to dimerize and displays no apparent affinity for the AP-1 element. Cotranslated c-Jun and c-Fos proteins bind 25 times more efficiently to the AP-1 DNA site as a heterodimer than does the c-Jun homodimer. These experiments suggest that in growth factor-stimulated cells c-Jun binds DNA as a dimer with c-Fos as its natural partner. However, overexpression of c-Jun protein in the absence of c-Fos may result in formation of aberrant homodimeric transcription complexes, which could abrogate the normal mechanisms controlling gene expression.
mesh_terms: D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D046911:Macromolecular Substances; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism* / Q000648:ultrastructure; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000378:metabolism* / Q000648:ultrastructure; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D014157:Transcription Factors; D004247:DNA