MafB, a new Maf family transcription activator that can associate with Maf and Fos but not with Jun.
We have identified a new member of the maf oncogene family and named it mafB. This gene is expressed in a wide variety of tissues and encodes a protein of 311 amino acids containing a typical bZip motif in its carboxy-terminal region. In the bZip domain, MafB shares extensive homology not only with v-Maf but also with other Maf-related proteins. As expected from its structure, MafB forms a homodimer through its leucine repeat structure and specifically binds Maf-recognition elements (MAREs). In addition, MafB forms heterodimers with v-Maf and Fos through its zipper structure. However, unlike v-Maf, MafB fails to associate with Jun. Transient cotransfection assays revealed that both v-Maf and MafB act as transactivators for a promoter linked to MAREs, although MafB is less potent than v-Maf. As is the case for the c-maf gene, overexpression of the mafB gene induces transformation of chicken embryo fibroblasts in vitro. Through formation of numerous bZip dimers, the Maf family proteins along with the AP-1 components should provide great diversity in transcriptional regulation for a wide variety of genes.
Kataoka
K
K
Department of Viral Oncology, Cancer Institute, Tokyo, Japan.
Fujiwara
K T
KT
Noda
M
M
Nishizawa
M
M
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins; D001483:Base Sequence; D001665:Binding Sites; D002645:Chickens; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D005260:Female; D051258:MafB Transcription Factor; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D009857:Oncogenes; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D014170:Transformation, Genetic
D030161:Avian Proteins; D004268:DNA-Binding Proteins; D051258:MafB Transcription Factor; C490406:Mafb protein, mouse; D015513:Oncogene Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D004247:DNA