The α and β subunits of the GA-binding protein form a stable heterodimer in solution -: Revised model of heterotetrameric complex assembly
The α and β subunits of the GA-binding protein form a stable heterodimer in solution -: Revised model of heterotetrameric complex assembly
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DOI：
10.1074/jbc.275.11.7749
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发表时间：
2000-03-17
影响因子：
4.8
通讯作者：
Martin, ME
中科院分区：
文献类型：
--
作者：
Chinenov, Y;Henzl, M;Martin, ME
我们研究了ga结合蛋白（GABP）在溶液中的组装，并确定了DNA在转录活性GABP α (2) β(2)异四聚体复合物组装中的作用。GABP与含有单个PEA3/ ets结合位点（PEA3/EBS）的DNA仅以ap异源二聚体复合物的形式结合，但极易在含有两个PEA3/EBS的DNA上以GABP α (2) β(2)异源四聚体复合物的形式结合。将PEA3/ ebs定位在DNA螺旋的同一面上，可以稳定异四聚体复合物的结合。这些观察结果表明，GABP α - β异二聚体是溶液中的主要分子种类，含有两个PEA3/ ebs的DNA促进GABP α (2) β(2)异四聚体复合物的形成。我们用超离心分析方法分析了GABP α (2) β(2)异质配合物在溶液中的组装。GABP α以单体形式存在于溶液中，而GABP β以单体-二聚体平衡存在（K-d = 1.8 +/- 0.27 μ M）。在两个亚基的等摩尔混合物中，GABP α和GABP β形成稳定的异源二聚体，没有检测到异源四聚体复合物。因此，GABP以异源二聚体的形式存在于溶液中，是一种弱的转录激活剂。转录活性GABP α (2) β(2)异四聚体复合体的组装需要含有至少两个PEA3/ ebs的特异性DNA的存在。
We have studied the assembly of GA-binding protein (GABP) in solution and established the sole of DNA in the assembly of the transcriptionally active GABP alpha(2)beta(2) heterotetrameric complex. GABP binds DNA containing a single PEA3/Ets-binding site (PEA3/EBS) exclusively as the ap heterodimer complex, but readily hinds as the GABP alpha(2)beta(2) heterotetramer complex on DNA containing two PEA3/EBSs. Positioning of the PEA3/EBSs on the same face of the DNA helix stabilizes heterotetramer complex binding. These observations suggest that GABP alpha beta heterodimers are the predominant molecular species in solution and that DNA containing two PEA3/ EBSs promotes formation of the GABP alpha(2)beta(2) heterotetrameric complex. We analyzed the assembly of GABP alpha(2)beta(2) heteromeric complexes in solution by analytical ultracentrifugation. GABP alpha exists as a monomer in solution while GABP beta exists in a monomer-dimer equilibrium (K-d = 1.8 +/- 0.27 mu M). In equimolar mixtures of the two subunits, GABP alpha and GABP beta formed a stable heterodimer, with no heterotetramer complex detected. Thus, GABP exists in solution as the heterodimer previously shown to be a weak transcriptional activator. Assembly of the transcriptionally active GABP alpha(2)beta(2) heterotetramer complex requires the presence of specific: DNA containing at least two PEA3/EBSs.