Involvement of a di-leucine motif in targeting of ABCC1 to the basolateral plasma membrane of polarized epithelial cells
Involvement of a di-leucine motif in targeting of ABCC1 to the basolateral plasma membrane of polarized epithelial cells
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DOI：
10.1016/j.bbrc.2013.10.013
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发表时间：
2013-11-08
影响因子：
3.1
通讯作者：
Sakaguchi, Masao
中科院分区：
文献类型：
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作者：
Emi, Yoshikazu;Harada, Yasue;Sakaguchi, Masao
三磷酸腺苷结合盒转运体异构体(ABCC1)定位于极化细胞的基侧膜，对于多种细胞代谢物的输出是至关重要的；然而，调控转运体基侧靶向的机制尚不清楚。在这里，我们描述了在人ABCC1的第一个细胞质环域(CLD1)中识别基侧靶向信号。ABCC1和ABCC2的CLD1氨基酸序列比较表明，ABCC1具有一个特征序列E(295)EVEALI(301)，它由一簇酸性谷氨酸残基和一个二亮氨酸基序组成。这一特征序列在脊椎动物ABCC1同源基因中高度保守，并且位于与ABCC2中描述的顶端靶向信号在结构上等效的位置。该序列在全长人ABCC1中的丙氨酸扫描突变表明，在极化的HepG2和MDCK细胞中，ABCC1的碱基侧向靶向都需要L-300和I-301残基。相反，转运蛋白的基侧定位不需要E-295、E-296和E-298残基。因此，CLD1中的二亮氨酸基序是ABCC1的碱侧靶向决定因素。(C)2013 Elsevier Inc.保留所有权利。
Localization of ATP-binding cassette transporter isoform Cl (ABCC1) to the basolateral membrane of polarized cells is crucial for export of a variety of cellular metabolites; however, the mechanism regulating basolateral targeting of the transporter is poorly understood. Here we describe identification of a basolateral targeting signal in the first cytoplasmic loop domain (CLD1) of human ABCC1. Comparison of the CLD1 amino acid sequences from ABCC1 to ABCC2 revealed that ABCC1 possesses a characteristic sequence, E(295)EVEALI(301), which is comprised of a cluster of acidic glutamate residues followed by a dileucine motif. This characteristic sequence is highly conserved among vertebrate ABCC1 orthologs and is positioned at a site that is structurally equivalent to the apical targeting signal previously described in ABCC2. Alanine scanning mutagenesis of this sequence in full-length human ABCC1 showed that both L-300 and I-301 residues were required for basolateral targeting of ABCC1 in polarized HepG2 and MDCK cells. Conversely, E-295, E-296, and E-298 residues were not required for basolateral localization of the transporter. Therefore, a di-leucine motif within the CLD1 is a basolateral targeting determinant of ABCC1. (C) 2013 Elsevier Inc. All rights reserved.