The Xenopus B2 factor involved in TFIIIA gene regulation is closely related to Sp1 and interacts in a complex with USF.
The Xenopus B2 factor involved in TFIIIA gene regulation is closely related to Sp1 and interacts in a complex with USF.
复制标题
参与 TFIIIA 基因调控的非洲爪蟾 B2 因子与 Sp1 密切相关，并与 USF 形成复合物相互作用。
DOI：
10.1016/s0378-1119(03)00384-6
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发表时间：
2003
期刊：
影响因子：
3.5
通讯作者：
Taylor,WilliamL
中科院分区：
文献类型：
--
作者：
Penberthy,WilliamT;Griffin,David;Hall,RobertK;Taylor,WilliamL
In the Xenopuslaevis oocyte there is a million fold more transcription factor IIIA (TFIIIA) and its corresponding mRNA than in a somatic cell. These high levels of TFIIIA gene expression are achieved primarily by transcriptional regulation. The TATA box along with three positive cis-elements in the control region of the TFIIIA gene located at positions −269 to −264 (E1), −235 to −220 (E2), and −669 to −636 (E3) are required for this high level of expression in oocytes. The proteins that bind E1 and E3 of the TFIIIA gene have been identified as Xenopus USF (Xl-USF) and B3 (homolog of Vg1 RBP/VERA). In this study the B2 protein was found to bind E2 in a zinc-dependent fashion and anti-human Sp1 (but not Sp2, Sp3, nor Sp4) supershifted the B2:element 2 complex. The E2 binding protein was purified by DNA affinity chromatography. Based on supershift analysis, molecular weight estimation experiments, and purified human Sp1 DNA binding affinity tests the data strongly support the idea that the B2 protein is the Xenopus ortholog of Sp1, but not Sp2, Sp3, nor Sp4. Xl-USF binds to element 1 of the TFIIIA gene which is immediately adjacent to element 2. Coimmunoprecipitation experiments using crude whole oocyte extracts revealed that Xenopus Sp1 and USF or closely related factors are present together in a high-affinity complex. This structure contributes positively to the initiation of TFIIIA gene transcription in Xenopus oocytes.
