Allegretto E A, Smeal T, Angel P, Spiegelman B M, Karin M
Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla 92093.
J Cell Biochem. 1990 Apr;42(4):193-206. doi: 10.1002/jcb.240420403.
Transcription factor AP-1 mediates induction of a set of genes in response to the phorbol ester tumor promoter TPA. Recently, AP-1 preparations from HeLa cells were shown to contain a product of the c-JUN protooncogene (Jun/AP-1) which forms a tight complex with the Fos protein. In this paper, we examine the role of the Fos protein in the DNA-binding activity of the AP-1 complex. We show that the DNA-binding activity of bacterially expressed trpE-Jun fusion proteins is increased many-fold upon their interaction with Fos (or a Fos-related antigen) expressed from a baculovirus vector. The site of Fos interaction is within the DNA-binding domain of Jun/AP-1, and anti-Fos antibodies interfere with the binding of affinity purified AP-1 to DNA. These results suggest that, by associating with Jun/AP-1, Fos is responsible for the formation of a multimeric protein complex that has greater affinity for the target sequence than does Jun/AP-1 alone.
转录因子AP-1介导一组基因的诱导表达以响应佛波酯肿瘤启动子TPA。最近，研究表明来自HeLa细胞的AP-1制剂含有c-JUN原癌基因的产物（Jun/AP-1），它与Fos蛋白形成紧密复合物。在本文中，我们研究了Fos蛋白在AP-1复合物DNA结合活性中的作用。我们发现，细菌表达的trpE-Jun融合蛋白与杆状病毒载体表达的Fos（或Fos相关抗原）相互作用后，其DNA结合活性增加了许多倍。Fos相互作用的位点在Jun/AP-1的DNA结合结构域内，抗Fos抗体干扰亲和纯化的AP-1与DNA的结合。这些结果表明，通过与Jun/AP-1结合，Fos负责形成一种多聚体蛋白复合物，该复合物对靶序列的亲和力比单独的Jun/AP-1更高。
