Biased ligands of G protein-coupled receptors (GPCRs) may have improved therapeutic benefits and safety profiles. However, the molecular mechanism of GPCR biased signaling remains largely unknown. Using apelin receptor (APJ) as a model, we systematically investigated the potential effects of amino acid residues around the orthosteric binding site on biased signaling. We discovered that a single residue mutation I109A (I1093.32) in the transmembrane domain 3 (TM3) located in the deep ligand-binding pocket was sufficient to convert a balanced APJ into a G protein signaling biased receptor. APJ I109A mutant receptor retained full capabilities in ligand binding and G protein activation, but was defective in GRK recruitment, β-arrestin recruitment, and downstream receptor-mediated ERK activation. Based on molecular dynamics simulations, we proposed a molecular mechanism for biased signaling of I109A mutant receptor. We postulate that due to the extra space created by I109A mutation, the phenyl group of the last residue (Phe-13) of apelin rotates down and initiates a cascade of conformational changes in TM3. Phe-13 formed a new cluster of hydrophobic interactions with the sidechains of residues in TM3, including F1103.33 and M1133.36, which stabilizes the mutant receptor in a conformation favoring biased signaling. Interruption of these stabilizing interactions by double mutation F110A/I109A or M113A/I109A largely restored the β-arrestin-mediated signaling. Taken together, we describe herein the discovery of a biased APJ mutant receptor and provide detailed molecular insights into APJ signaling selectivity, facilitating the discovery of novel therapeutics targeting APJ.
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The cover image represents the scheme of DNA-linked inhibitor antibody assay (DIANA) as a new method for screening influenza neuraminidase inhibitors, described in this issue by Kožíšek et al. For further details, see pages 3847–3860.
Research Article|
December 06 2018
GPCR structure and function relationship: identification of a biased apelin receptor mutant
Ting Ban;
Ting Ban
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Xun Li;
Xun Li
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Xiaochuan Ma;
Xiaochuan Ma
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Hui Yang;
Hui Yang
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Yunpeng Song;
Yunpeng Song
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Yaping Sun;
Yaping Sun
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Michelle Shen;
Michelle Shen
2Amgen Research, Amgen Inc., One Amgen Center Dr., Thousand Oaks, CA 91320, U.S.A.
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Na Li;
Na Li
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Mei-Yun Zhang;
Mei-Yun Zhang
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Yingli Ma;
Yingli Ma
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Wenge Zhong;
Wenge Zhong
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Mingqiang Zhang;
Mingqiang Zhang
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
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Liaoyuan A. Hu
1Amgen Asia R&D Center, Amgen Biopharmaceutical R&D (Shanghai) Co., Ltd, Shanghai 201210, China
Correspondence: Liaoyuan A. Hu (liaoyuan@amgen.com)
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Publisher: Portland Press Ltd
Received:
September 11 2018
Revision Received:
November 06 2018
Accepted:
November 07 2018
Accepted Manuscript online:
November 08 2018
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2018
Biochem J (2018) 475 (23): 3813–3826.
Article history
Received:
September 11 2018
Revision Received:
November 06 2018
Accepted:
November 07 2018
Accepted Manuscript online:
November 08 2018
Citation
Ting Ban, Xun Li, Xiaochuan Ma, Hui Yang, Yunpeng Song, Yaping Sun, Michelle Shen, Na Li, Mei-Yun Zhang, Yingli Ma, Wenge Zhong, Mingqiang Zhang, Liaoyuan A. Hu; GPCR structure and function relationship: identification of a biased apelin receptor mutant. Biochem J 12 December 2018; 475 (23): 3813–3826. doi: https://doi.org/10.1042/BCJ20180740
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