Characterization of the Ah receptor-associated protein, ARA9
Characterization of the Ah receptor-associated protein, ARA9
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DOI：
10.1074/jbc.273.50.33580
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发表时间：
1998-12-11
影响因子：
4.8
通讯作者：
Bradfield, CA
中科院分区：
文献类型：
--
作者：
Carver, LA;LaPres, JJ;Bradfield, CA
未配体的芳香烃受体（AHR）与其他蛋白质形成复合物，包括90 kDa的热休克蛋白（Hsp 90）和37 kDa的ARA 9蛋白质。我们发现，在ARA 9的COOH末端发现的三个tetratricopeptide重复序列是必要的，足以与AHR复合物的相互作用。相反，AHR的“阻遏物”/Hsp 90结合结构域是与ARA 9相互作用所必需的。由于ARA 9与未配体糖皮质激素受体（GR）复合物中发现的52 kDa FK 506结合蛋白（FKBP 52）非常相似，我们比较了ARA 9和FKBP 52对AHR和GR的结合特异性。在免疫共沉淀实验中，ARA 9特异性与AHR-Hsp 90复合物结合，但不与GR-Hsp 90复合物结合。此外，ARA 9显示出比FKBP 52更大的与AHR-Hsp 90复合物缔合的能力。在酵母表达系统中，ARA 9表达增强了AHR对激动剂β-萘酮的反应，使EC降低了5倍以上，最大反应增加了2.5倍，这表明了这种相互作用的生物学重要性。相反，FKBP 52的共表达对AHR信号传导没有影响。此外，尽管ARA 9含有与其他FK 506结合蛋白相似的结构域，但不能检测到ARA 9与H-3-FK 506的结合。最后，我们已经确定了ARA 9在发育中的小鼠胚胎中的发育和表达模式，并将ARA 9基因定位于人类染色体11q13.3。
The unliganded aryl hydrocarbon receptor (AHR) is found in a complex with other proteins including the 90-kDa heat shock protein (Hsp90) and a 37-kDa protein we refer to as ARA9. We found that the three tetratricopeptide repeats found in the COOH terminus of ARA9 are necessary and sufficient for interaction with the AHR complex. Conversely, the AHR's "repressor"/Hsp90 binding domain is required for interaction with ARA9. Because ARA9 closely resembles the 52-kDa FK506-binding protein (FKBP52), found in the unliganded glucocorticoid receptor (GR) complex, we compared the binding specificities of ARA9 and FKBP52 for AHR and GR. In co-immunoprecipitation experiments, ARA9 specifically associated with AHR-Hsp90 complex but not with GR-Hsp90 complexes. In addition, ARA9 showed a greater capacity than FKBP52 to associate with AHR-Hsp90 complexes. The biological importance of this interaction was suggested by the observation that in a yeast expression system ARA9 expression enhanced the response of AHR to the agonist beta-napthoflavone, decreasing the EC,, by greater than 5-fold and increasing the maximal response 2.5-fold. In contrast, co-expression of FKBP52 had no effect on AHR signaling. In addition, although ARA9 contains a domain similar to that found in other FK506-binding proteins, ARA9 binding to H-3-FK506 could not be detected. Finally, we have characterized the developmental and expression pattern of ARA9 in the developing mouse embryo and mapped the ARA9 locus to human chromosome 11q13.3.