A multifunctional DNA-binding protein that promotes the formation of serum response factor homeodomain complexes: identity to TFII-I
A multifunctional DNA-binding protein that promotes the formation of serum response factor homeodomain complexes: identity to TFII-I
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DOI：
10.1101/gad.11.19.2482
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发表时间：
1997-10-01
影响因子：
10.5
通讯作者：
Gilman, M
中科院分区：
文献类型：
--
作者：
Grueneberg, DA;Henry, RW;Gilman, M
人同源结构域蛋白Phox1与血清应答因子（SRF）在功能上相互作用，以在HeLa细胞共转染测定中赋予SRF结合位点血清应答转录活性。然而，稳定的三元复合物组成的SRF，Phox1，和DNA，这可能是介导的Phox1在体内的转录作用，尚未在体外观察到。在这里，我们报告的鉴定，纯化和分子克隆的人类蛋白质，促进形成稳定的高阶复合物的SRF和Phox1。我们发现，这种蛋白质，称为SPIN，在体外和体内与SRF和Phox1相互作用。此外，SPIN特异性结合到c-fos启动子中的多个序列，并与Phox1协同作用，以促进由c-fos血清反应元件（SRE）驱动的报告基因的血清诱导型转录。SPIN与起始物结合蛋白TFII-I相同。与此假设一致，SPIN在体外对特征化的起始序列表现出适度的亲和力。我们建议，这种多功能的蛋白质协调形成一个积极的启动子复合物在c-fos基因，包括特定的信号响应激活复合物的一般转录机器的连接。
The human homeodomain protein Phox1 interacts functionally with serum response factor (SRF) to impart serum responsive transcriptional activity to SRF-binding sites in a HeLa cell cotransfection assay. However, stable ternary complexes composed of SRF, Phox1, and DNA, which presumably mediate the transcriptional effects of Phox1 in vivo, have not been observed in vitro. Here, we report the identification, purification, and molecular cloning of a human protein that promotes the formation of stable higher-order complexes of SRF and Phox1. We show that this protein, termed SPIN, interacts with SRF and Phox1 in vitro and in vivo. Furthermore, SPIN binds specifically to multiple sequences in the c-fos promoter and interacts cooperatively with Phox1 to promote serum-inducible transcription of a reporter gene driven by the c-fos serum response element (SRE). SPIN is identical to the initiator-binding protein TFII-I. Consistent with this hypothesis, SPIN exhibits modest affinity for a characterized initiator sequence in vitro. We propose that this multifunctional protein coordinates the formation of an active promoter complex at the c-fos gene, including the linkage of specific signal responsive activator complexes to the general transcription machinery.