Involvement of a di-leucine motif in targeting of ABCC1 to the basolateral plasma membrane of polarized epithelial cells

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• 作者：Yoshikazu Emi ; Yasue Harada ; Masao Sakaguchi
• 关键词：ABCC1 ; ATP-binding cassette transporter isoform C1 ; APN ; aminopeptidase-N ; ATS ; apical targeting sequence ; CLD ; cytoplasmic loop domain ; HA ; hemagglutinin ; MCC ; Manders&rsquo ; correlation coefficient ; MSD ; membrane spanning domain ; Na ; K-ATPase ; Na+ ; K+-ATPase 伪1 subunit ; NBD ; nucleotide binding domain
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：8 November, 2013
• 年：2013
• 卷：441
• 期：1
• 页码：89-95
• 全文大小：3469 K

文摘

Localization of ATP-binding cassette transporter isoform C1 (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, E²⁹⁵EVEALI³⁰¹, which is comprised of a cluster of acidic glutamate residues followed by a di-leucine 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 L³⁰⁰ and I³⁰¹ residues were required for basolateral targeting of ABCC1 in polarized HepG2 and MDCK cells. Conversely, E²⁹⁵, E²⁹⁶, and E²⁹⁸ 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.