Rat maf-related factors: the specificities of DNA binding and heterodimer formation.
maf is a family of genes encoding bZIP transcription factors. We isolated two cellular maf-related cDNAs, maf-1 (mafB) and maf-2 (c-maf), from rat and determined the specificities of DNA binding and heterodimer formation. Although both Mafs strongly bind to MARE, the consensus Maf recognition sequence (MARE, -TGCTGACTCAGCA-), originally identified by v-Maf protein Maf-1, recognizes a number of sequences containing only the first half of the MARE, -GCTGAC-. On the other hand, no such consensus short sequence could be determined for Maf-2. We determined the specificities of heterodimer formation with all members of the Jun and Fos family. In contrast to v-Maf which forms heterodimers with all Jun and Fos proteins, Maf-1 heterodimerizes with all four Fos proteins, but not at all with the three Jun proteins. Maf-2 heterodimerizes with c-Fos. We have also found that heterodimer formation of Maf-2 with c-Fos dramatically changes the specificity of DNA binding and trans-activation activity from that of the Maf-2 homodimer. These results show that Maf-1 and Maf-2 have significantly different properties and they might have different target genes and functions, in spite of the similarity of their bZip domain structure.
Matsushima-Hibiya
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Y
Department of Biochemistry, School of Medicine, Hokkaido University, Sapporo, Japan.
Nishi
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Sakai
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M
D000818:Animals; D030161:Avian Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D016384:Consensus Sequence / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D051790:G-Box Binding Factors; D051258:MafB Transcription Factor; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D015513:Oncogene Proteins / Q000378:metabolism*; D011487:Protein Conformation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051257:Proto-Oncogene Proteins c-maf; D051381:Rats; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics
D030161:Avian Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; C495609:Maf protein, rat; D051258:MafB Transcription Factor; C490405:Mafb protein, rat; D009838:Oligodeoxyribonucleotides; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D051257:Proto-Oncogene Proteins c-maf; D015534:Trans-Activators; D014157:Transcription Factors