title: A new group of conserved coactivators that increase the specificity of AP-1 transcription factors.
abstract: The Jun proteins are nuclear proteins that combine with Fos proteins to form a gene-regulatory protein, AP-1. They have highly conserved DNA-binding and dimerization domains, resulting in almost identical sequence-recognition properties. Nevertheless, there are many indications that each Jun protein activates a distinct and only partially overlapping set of AP-1 target genes. Using the more variable activation domain of c-Jun as a bait, we identified a protein, JAB1, that interacts with c-Jun and JunD, but not with JunB or v-Jun. As a result, JAB1 selectively potentiates transactivation by only c-Jun or JunD. In vitro, JAB1 specifically stabilizes complexes of c-Jun or JunD with AP-1 sites and does not affect binding of either JunB or v-Jun. The amino-terminal half of JAB1 is very similar to the amino terminal region of Pad1 from fission yeast, which was identified genetically as a coactivator of a subset of AP-1 target genes. JAB1 and Pad1 are also functionally interchangeable. They define a new group of coactivators that increase the specificity of target gene activation by AP-1 proteins.
authors.affiliation: Department of Pharmacology, Program in Biomedical Sciences, School of Medicine, University of California, San Diego, La Jolla 92093-0636, USA.
authors.forename: F X
authors.initials: FX
authors.lastname: Claret
authors.forename: M
authors.initials: M
authors.lastname: Hibi
authors.forename: S
authors.initials: S
authors.lastname: Dhut
authors.forename: T
authors.initials: T
authors.lastname: Toda
authors.forename: M
authors.initials: M
authors.lastname: Karin
mesh_terms: D000595:Amino Acid Sequence; D000075686:COP9 Signalosome Complex; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators / Q000737:chemistry; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016755:Proto-Oncogene Proteins c-jun; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C093857:rpn11 protein, S pombe; D010447:Peptide Hydrolases; C501488:COPS5 protein, human; D000075686:COP9 Signalosome Complex