Abate C, Luk D, Curran T
Department of Molecular Oncology and Virology, Roche Research Center, Nutley, New Jersey 07110.
Cell Growth Differ. 1990 Oct;1(10):455-62.
The protooncogenes c-fos and c-jun encode nuclear proteins (fos and jun, respectively) that function cooperatively as a heterodimeric protein complex in the regulation of gene transcription. These proteins dimerize via a structural motif known as the leucine zipper and bind to activator protein-1 sites via a conserved domain that is rich in basic amino acids. Previously, we demonstrated that while fos and jun polypeptides expressed in Escherichia coli dimerize efficiently, they exhibit only a low level of DNA-binding activity. Here we show that the DNA-binding activity of fos-jun heterodimers and jun-jun homodimers is stimulated dramatically by a ubiquitous nuclear protein. This protein does not appear to participate in the DNA-protein complex, and it does not affect the specificity of the interaction with DNA. These results suggest that a nuclear protein regulates the DNA-binding activity of fos and jun indirectly.
原癌基因c-fos和c-jun分别编码核蛋白（分别为fos和jun），它们作为异二聚体蛋白复合物协同作用于基因转录的调控。这些蛋白通过一种称为亮氨酸拉链的结构基序形成二聚体，并通过富含碱性氨基酸的保守结构域与激活蛋白-1位点结合。此前，我们证明，虽然在大肠杆菌中表达的fos和jun多肽能高效形成二聚体，但它们仅表现出低水平的DNA结合活性。在此我们表明，一种普遍存在的核蛋白能显著刺激fos-jun异二聚体和jun-jun同二聚体的DNA结合活性。这种蛋白似乎不参与DNA-蛋白质复合物的形成，也不影响与DNA相互作用的特异性。这些结果表明，一种核蛋白间接调节fos和jun的DNA结合活性。
