title: USF2/FIP associates with the b-Zip transcription factor, c-Maf, via its bHLH domain and inhibits c-Maf DNA binding activity.
abstract: In screening for proteins that interact with the basic zipper (bZip) transcription factor, c-Maf, we isolated USF2/FIP. USF2 is a member of the bHLH-Zip protein family, possessing a basic (b) DNA binding region, a helix-loop-helix (HLH) motif, and a leucine zipper (Zip) structure. Mutants of USF2 that lacked a Zip formed heterodimers with c-Maf, but did not homodimerize. Deletion of the USF2 basic region or mutation of its helices abrogated its binding to c-Maf, but had no effect on homodimerization. A functional c-Maf bZip motif was necessary for both homodimerization and heterodimerization with USF2. These data suggest a tetrameric configuration for Maf-USF2 complexes. In the presence of USF2, the DNA binding activity of c-Maf was markedly reduced. Therefore, USF2 and c-Maf may interact to regulate gene expression.
authors.affiliation: Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: C
authors.initials: C
authors.lastname: Kurschner
authors.forename: J I
authors.initials: JI
authors.lastname: Morgan
mesh_terms: D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites; D001704:Biopolymers; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051790:G-Box Binding Factors; D018257:Helix-Loop-Helix Motifs; D007608:Kainic Acid / Q000494:pharmacology; D016350:Leucine Zippers; D009419:Nerve Tissue Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051257:Proto-Oncogene Proteins c-maf; D011994:Recombinant Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D051720:Upstream Stimulatory Factors
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D001704:Biopolymers; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D051257:Proto-Oncogene Proteins c-maf; C091104:Purkinje cell protein L7; D011994:Recombinant Proteins; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors; D003513:Cycloheximide; D007608:Kainic Acid