Potent transactivation domains of the Ah receptor and the Ah receptor nuclear translocator map to their carboxyl termini.
Potent transactivation domains of the Ah receptor and the Ah receptor nuclear translocator map to their carboxyl termini.
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DOI：
10.1016/s0021-9258(18)31725-3
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发表时间：
1994-12
期刊：
影响因子：
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通讯作者：
Sanjay Jain;K. M. Dolwick;J. Schmidt;Christopher A. Bradfield
中科院分区：
文献类型：
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作者：
Sanjay Jain;K. M. Dolwick;J. Schmidt;Christopher A. Bradfield
Ah受体（AHR）是一种配体激活的转录因子，在结构上与其二聚化伴侣、Ah受体核转运蛋白（ARNT）以及两种果蝇蛋白SIM和PER相关。所有四种蛋白质都含有一个同源区域，现在称为PAS同源结构域。此外，AHR、ARNT和SIM在其N末端具有碱性区螺旋-环-螺旋基序，而PER没有。以前的AHR映射研究表明，PAS结构域包含配体识别，二聚化，并与90 kDa的热休克蛋白相互作用所需的序列。他们还证实了碱性区螺旋-环-螺旋结构域在二聚化和序列特异性DNA结合中起作用。为了确定参与靶基因的反式激活的结构域，我们产生了嵌合体的AHR/ARNT缺失突变体与酵母Gal 4蛋白的DNA结合区，瞬时表达这些在COS-1细胞中，并监测其能力激活氯霉素乙酰转移酶报告基因的控制下的最小启动子驱动的增强子元件由Gal 4识别。对这些融合的广泛分析显示，AHR和ARNT在其C末端内具有有效的反式激活结构域。重要的是，发现AHR和ARNT的氨基末端的一半都没有反式激活活性。
The Ah receptor (AHR) is a ligand-activated transcription factor that is structurally related to its dimerization partner, the Ah receptor nuclear translocator (ARNT), and two Drosophila proteins, SIM and PER. All four proteins contain a region of homology now referred to as a PAS homology domain. In addition, the AHR, ARNT, and SIM harbor a basic region helix-loop-helix motif in their N termini, whereas PER does not. Previous mapping studies of the AHR have demonstrated that the PAS domain contains sequences required for ligand recognition, dimerization, and interaction with the 90-kDa heat shock protein. They also have confirmed that the basic region helix-loop-helix domain plays a role in both dimerization and sequence-specific DNA binding. To identify domains involved in transactivation of target genes, we generated chimeras of AHR/ARNT deletion mutants with the DNA binding region of the yeast Gal4 protein, transiently expressed these in COS-1 cells, and monitored their capacity to activate the chloramphenicol acetyltransferase reporter gene under the control of a minimal promoter driven by enhancer elements recognized by Gal4. Extensive analysis of these fusions revealed that the AHR and ARNT harbor potent transactivation domains within their C termini. Importantly, the amino-terminal halves of both the AHR and ARNT were found to be devoid of transactivation activity.