Kataoka K, Fujiwara K T, Noda M, Nishizawa M
Department of Viral Oncology, Cancer Institute, Tokyo, Japan.
Mol Cell Biol. 1994 Nov;14(11):7581-91. doi: 10.1128/mcb.14.11.7581-7591.1994.
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.
我们鉴定出了maf癌基因家族的一个新成员，并将其命名为mafB。该基因在多种组织中表达，编码一个含有311个氨基酸的蛋白质，其羧基末端区域含有一个典型的bZip基序。在bZip结构域中，MafB不仅与v-Maf，而且与其他Maf相关蛋白具有广泛的同源性。正如从其结构所预期的那样，MafB通过其亮氨酸重复结构形成同源二聚体，并特异性结合Maf识别元件（MAREs）。此外，MafB通过其拉链结构与v-Maf和Fos形成异源二聚体。然而，与v-Maf不同，MafB不能与Jun结合。瞬时共转染试验表明，v-Maf和MafB都可作为与MAREs相连的启动子的反式激活因子，尽管MafB的活性比v-Maf弱。与c-maf基因的情况一样，mafB基因的过表达在体外诱导鸡胚成纤维细胞转化。通过形成众多的bZip二聚体，Maf家族蛋白与AP-1组分一起应该为多种基因的转录调控提供极大的多样性。
