Characterization of nuclear localization signals and cytoplasmic retention region in the nuclear receptor CAR
Characterization of nuclear localization signals and cytoplasmic retention region in the nuclear receptor CAR
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DOI：
10.1016/j.bbamcr.2005.06.012
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发表时间：
2005-09-10
影响因子：
5.1
通讯作者：
Inouye, Y
中科院分区：
文献类型：
--
作者：
Kanno, Y;Suzuki, M;Inouye, Y
组成型雄甾烷受体（CAR）是一种配体/激活剂依赖性反式激活因子，存在于细胞质中，形成一种尚未鉴定的蛋白质复合物的一部分。在刺激后，CAR易位到细胞核中，在那里它调节靶基因的反式激活。然而，在大鼠肝RL-34细胞中外源表达的CAR即使在没有激活剂的情况下也位于细胞核中。通过用各种突变的大鼠CAR片段瞬时转染RL-34细胞，我们鉴定了两种核定位信号：氨基酸100和108之间的碱性氨基酸富集序列（RRARQARRR）;以及配体结合结构域内广泛分布在氨基酸残基111至320上的非连续残基的组装。未发现与先前报道的鼠异种化学反应信号相对应的C-末端富含亮氨酸的片段在培养细胞中表现出核输入活性。使用用各种CAR片段转染的大鼠原代肝细胞，我们鉴定了CAR的胞质保留所需的区域。基于这些结果，CAR的细胞内定位将由核定位信号、异种化学反应信号和细胞质保留区的组合效应决定。(c)2005 Elsevier B. V.保留所有权利。
The constitutive androstane receptor (CAR) is a ligand/activator-dependent transactivation factor that resides in the cytoplasm and forms part of an as yet unidentified protein complex. Upon stimulation, CAR translocates into the nucleus where it modulates the transactivation of target genes. However, CAR exogenously expressed in rat liver RL-34 cells is located in the nucleus even in the absence of activators. By transiently transfecting RL-34 cells with various mutated rat CAR segments, we identified two nuclear localization signals: a basic amino acid-rich sequence (RRARQARRR) between amino acids 100 and 108; and an assembly of noncontiguous residues widely spread over amino acid residues 111 to 320 within the ligand binding domain. A C-terminal leucine-rich segment corresponding to a previously reported murine xenochemical response signal was not found to exhibit nuclear import activity in cultured cells. Using rat primary hepatocytes transfected with various CAR segments, we identified the region required for the cytoplasmic retention of CAR. Based on these results, the intracellular localization of CAR would be determined by the combined effects of nuclear localization signals, the xenochemical response signal, and the cytoplasmic retention region. (c) 2005 Elsevier B.V. All rights reserved.