Small Maf proteins heterodimerize with Fos and may act as competitive repressors of the NF-E2 transcription factor.
The maf oncogene encodes a bZip nuclear protein which recognizes sequences related to an AP-1 site either as a homodimer or as heterodimers with Fos and Jun. We describe here a novel maf-related gene, mafG, which shows extensive homology with two other maf-related genes, mafK and mafF. These three maf-related genes encode small basic-leucine zipper proteins lacking the trans-activator domain of v-Maf. Bacterially expressed small Maf proteins bind to DNA as homodimers with a sequence recognition profile that is virtually identical to that of v-Maf. As we have previously described, the three small Maf proteins also dimerize with the large subunit of NF-E2 (p45) to form an erythroid cell-specific transcription factor, NF-E2, which has distinct DNA-binding specificity. This study shows that the small Maf proteins can also dimerize among themselves and with Fos and a newly identified p45-related molecule (Ech) but not with v-Maf or Jun. Although the small Maf proteins preferentially recognize the consensus NF-E2 sequence as heterodimers with either NF-E2 p45, Ech, or Fos, these heterodimers seemed to be different in their transactivation potentials. Coexpression of Fos and small Mafs could not activate a promoter with tandem repeats of the NF-E2 site. These results raise the possibility that tissue-specific gene expression and differentiation of erythroid cells are regulated by competition among Fos, NF-E2 p45, and Ech for small Maf proteins and for binding sites.
Kataoka
K
K
Department of Viral Oncology, Cancer Institute, Tokyo, Japan.
Igarashi
K
K
Itoh
K
K
Fujiwara
K T
KT
Noda
M
M
Yamamoto
M
M
Nishizawa
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D050981:Erythroid-Specific DNA-Binding Factors; D005786:Gene Expression Regulation; D015698:Genomic Library; D008957:Models, Genetic; D008969:Molecular Sequence Data; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D051256:Oncogene Protein v-maf; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051257:Proto-Oncogene Proteins c-maf; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000378:metabolism*; D014764:Viral Proteins
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D051256:Oncogene Protein v-maf; D009856:Oncogene Proteins, Viral; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D051257:Proto-Oncogene Proteins c-maf; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; C495606:v-Maf protein, Avian retrovirus AS42