Functional analysis of activation and repression domains of the rainbow trout aryl hydrocarbon receptor nuclear translocator (rtARNT) protein isoforms.
Functional analysis of activation and repression domains of the rainbow trout aryl hydrocarbon receptor nuclear translocator (rtARNT) protein isoforms.
复制标题
虹鳟鱼芳基碳氢化合物受体核转位子 (rtARNT) 蛋白亚型的激活和抑制域的功能分析。
DOI：
10.1016/s0006-2952(99)00036-2
复制
发表时间：
1999
影响因子：
5.8
通讯作者：
Pollenz,RS
中科院分区：
文献类型：
--
作者：
Necela,B;Pollenz,RS
芳烃受体核转运体(ARNT)蛋白参与多种信号转导途径。彩虹鲑鱼表达不同亚型的Arnt蛋白，由于选择性的RNA剪接，这些蛋白在C-末端结构域上存在差异。彩虹鲑鱼ARNTb(RtARNTb)含有一个富含谷氨酰胺和天冬氨酸(QN)的C-末端结构域，而rtARNTab的C-末端结构域富含Pro、丝氨酸和苏氨酸(PST)。RtARNTB在AH受体介导的信号转导中起正作用，而rtARNTB负作用。为了了解两种rtARNT异构体C-末端结构域的变化如何影响功能，进行了研究。RtARNTb富含QN的C末端结构域的缺失不影响芳香烃受体(AHR)介导的信号转导功能，而rtARNTb富含PST的结构域的缺失则存储了功能。在截短的rtARNTbor小鼠ARNT(MARNT)上表达PST富含结构域(MARNT)使该蛋白的功能降低50-80%。凝胶漂移分析表明，PST富含结构域通过抑制AHR·Arnt异源二聚体的DNA结合而影响AHR介导的信号转导。Gal4反式激活实验显示，rtARNTb的富含qN结构域存在一个有效的反式激活结构域。相反，含有富含rtARNTaPST结构域的Gal4蛋白没有反式激活，因为这些蛋白不与DNA结合。对PST富含结构域的二级结构分析表明，该结构域具有亲水性和疏水性。截断横跨rtART最后20-40个氨基酸的疏水结构域，表明阻遏功能与蛋白质的错误折叠或基本DNA结合域的掩蔽有关。C末端结构域中的功能多样性与其他负作用转录因子是一致的，并说明了一个共同的生物学主题。
The aryl hydrocarbon receptor nuclear translocator (ARNT) protein is involved in many signaling pathways. Rainbow trout express isoforms of ARNT protein that are divergent in their C-terminal domains due to alternative RNA splicing. Rainbow trout ARNTb(rtARNTb) contains a C-terminal domain rich in glutamine and asparagine (QN), whereas the C-terminal domain of rtARNTais rich in proline, serine, and threonine (PST). rtARNTbfunctions positively in AH receptor-mediated signaling, whereas rtARNTafunctions negatively. Studies were performed to understand how changes in the C-terminal domains of the two rtARNT isoforms affect function. Deletion of the QN-rich C-terminal domain of rtARNTbdid not affect function in aryl hydrocarbon receptor (AHR)-mediated signaling, whereas deletion of the PST-rich domain of rtARNTarestored function. Expression of the PST-rich domain on truncated rtARNTbor mouse ARNT (mARNT) reduced function of this protein by 50–80%. Gel shift assays revealed that the PST-rich domain affected AHR-mediated signaling by inhibiting DNA binding of the AHR•ARNT heterodimer. Gal4 transactivation assays revealed a potent transactivation domain in the QN-rich domain of rtARNTb. In contrast, Gal4 proteins containing the PST-rich domain of rtARNTadid not transactivate because the proteins did not bind to DNA. Secondary structure analysis of the PST-rich domain revealed hydrophilic and hydrophobic regions. Truncation of the hydrophobic domain that spanned the final 20–40 amino acids of the rtARNTarestored function to the protein, suggesting that repressor function was related to protein misfolding or masking of the basic DNA binding domain. Functional diversity within the C-terminal domain is consistent with other negatively acting transcription factors and illustrates a common biological theme.