Yokogawa, Mariko



Faculty of Pharmacy, Department of Pharmaceutical Sciences 生命機能物理学講座 (Shiba-Kyoritsu)


Assistant Professor/Senior Assistant Professor

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Academic Degrees 【 Display / hide

  • 博士(薬学), The University of Tokyo, Coursework

Licenses and Qualifications 【 Display / hide

  • 薬剤師免許


Research Areas 【 Display / hide

  • Physical pharmacy

  • Structural biochemistry

Research Keywords 【 Display / hide

  • NMR

  • イオンチャネル

  • 構造生物学

  • 膜タンパク質


Papers 【 Display / hide

  • Mechanism of hERG inhibition by gating-modifier toxin, APETx1, deduced by functional characterization

    Matsumura K., Shimomura T., Kubo Y., Oka T., Kobayashi N., Imai S., Yanase N., Akimoto M., Fukuda M., Yokogawa M., Ikeda K., Kurita J.i., Nishimura Y., Shimada I., Osawa M.

    BMC Molecular and Cell Biology 22 ( 3 )  2021.01

    Research paper (scientific journal), Joint Work, Accepted

     View Summary

    Background: Human ether-à-go-go-related gene potassium channel 1 (hERG) is a voltage-gated potassium channel, the voltage-sensing domain (VSD) of which is targeted by a gating-modifier toxin, APETx1. APETx1 is a 42-residue peptide toxin of sea anemone Anthopleura elegantissima and inhibits hERG by stabilizing the resting state. A previous study that conducted cysteine-scanning analysis of hERG identified two residues in the S3-S4 region of the VSD that play important roles in hERG inhibition by APETx1. However, mutational analysis of APETx1 could not be conducted as only natural resources have been available until now. Therefore, it remains unclear where and how APETx1 interacts with the VSD in the resting state. Results: We established a method for preparing recombinant APETx1 and determined the NMR structure of the recombinant APETx1, which is structurally equivalent to the natural product. Electrophysiological analyses using wild type and mutants of APETx1 and hERG revealed that their hydrophobic residues, F15, Y32, F33, and L34, in APETx1, and F508 and I521 in hERG, in addition to a previously reported acidic hERG residue, E518, play key roles in the inhibition of hERG by APETx1. Our hypothetical docking models of the APETx1-VSD complex satisfied the results of mutational analysis. Conclusions: The present study identified the key residues of APETx1 and hERG that are involved in hERG inhibition by APETx1. These results would help advance understanding of the inhibitory mechanism of APETx1, which could provide a structural basis for designing novel ligands targeting the VSDs of KV channels.

  • Structural mechanism underlying G protein family-specific regulation of G protein-gated inwardly rectifying potassium channel

    Kano H., Toyama Y., Imai S., Iwahashi Y., Mase Y., Yokogawa M., Osawa M., Shimada I.

    Nature Communications 10 ( 1 )  2019.12

    Research paper (scientific journal), Joint Work, Accepted

     View Summary

    G protein-gated inwardly rectifying potassium channel (GIRK) plays a key role in regulating neurotransmission. GIRK is opened by the direct binding of the G protein βγ subunit (Gβγ), which is released from the heterotrimeric G protein (Gαβγ) upon the activation of G protein-coupled receptors (GPCRs). GIRK contributes to precise cellular responses by specifically and efficiently responding to the Gi/o-coupled GPCRs. However, the detailed mechanisms underlying this family-specific and efficient activation are largely unknown. Here, we investigate the structural mechanism underlying the Gi/o family-specific activation of GIRK, by combining cell-based BRET experiments and NMR analyses in a reconstituted membrane environment. We show that the interaction formed by the αA helix of Gαi/o mediates the formation of the Gαi/oβγ-GIRK complex, which is responsible for the family-specific activation of GIRK. We also present a model structure of the Gαi/oβγ-GIRK complex, which provides the molecular basis underlying the specific and efficient regulation of GIRK.

  • Nanodiscs for structural biology in a membranous environment

    Yokogawa M., Fukuda M., Osawa M.

    Chemical and Pharmaceutical Bulletin 67 ( 4 ) 321 - 326 2019

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  00092363

     View Summary

    The structures of many membrane proteins have been analyzed in detergent micelles. However, the environment of detergent micelles differs somewhat from that of the lipid bilayer, where membrane proteins exhibit physiological functions. Therefore, a more membrane-like environment has been awaited for structural analysis of membrane proteins. Nanodiscs are “hockey-puck”-shaped lipid bilayer particles that distribute in a monodispersed manner in aqueous solution. We review how nanodiscs or protein-reconstituted nanodiscs are prepared and how they are utilized to analyze protein structure, dynamics, and interactions with lipid molecules using solution NMR and cryo-electron microscopy.

  • Structural basis for the ethanol action on G-protein-activated inwardly rectifying potassium channel 1 revealed by NMR spectroscopy.

    Toyama Y, Kano H, Mase Y,Yokogawa M, Osawa M, Shimada I

    Proc Natl Acad Sci U S A. 115 ( 15 ) 3858 - 3863 2018.03

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  00278424

     View Summary

    Ethanol consumption leads to a wide range of pharmacological effects by acting on the signaling proteins in the human nervous system, such as ion channels. Despite its familiarity and biological importance, very little is known about the molecular mechanisms underlying the ethanol action, due to extremely weak binding affinity and the dynamic nature of the ethanol interaction. In this research, we focused on the primary in vivo target of ethanol, G-protein-activated inwardly rectifying potassium channel (GIRK), which is responsible for the ethanol-induced analgesia. By utilizing solution NMR spectroscopy, we characterized the changes in the structure and dynamics of GIRK induced by ethanol binding. We demonstrated here that ethanol binds to GIRK with an apparent dissociation constant of 1.0 M and that the actual physiological binding site of ethanol is located on the cavity formed between the neighboring cytoplasmic regions of the GIRK tetramer. From the methyl-based NMR relaxation analyses, we revealed that ethanol activates GIRK by shifting the conformational equilibrium processes, which are responsible for the gating of GIRK, to stabilize an open conformation of the cytoplasmic ion gate. We suggest that the dynamic molecular mechanism of the ethanol-induced activation of GIRK represents a general model of the ethanol action on signaling proteins in the human nervous system.

  • Characterization of the multimeric structure of poly(A)-binding protein on a poly(A) tail.

    Ryoichi Sawazaki, Shunsuke Imai, Mariko Yokogawa,Nao Hosoda, Shin-ichi Hoshino, Muneyo Mio, Kazuhiro Mio, Ichio Shimada, and Masanori Osawa

    Sci. Rep. 8 ( 1 ) 1455 2018.01

    Research paper (scientific journal), Joint Work, Accepted

     View Summary

    Eukaryotic mature mRNAs possess a poly adenylate tail (poly(A)), to which multiple molecules of poly(A)-binding protein C1 (PABPC1) bind. PABPC1 regulates translation and mRNA metabolism by binding to regulatory proteins. To understand functional mechanism of the regulatory proteins, it is necessary to reveal how multiple molecules of PABPC1 exist on poly(A). Here, we characterize the structure of the multiple molecules of PABPC1 on poly(A), by using transmission electron microscopy (TEM), chemical cross-linking, and NMR spectroscopy. The TEM images and chemical cross-linking results indicate that multiple PABPC1 molecules form a wormlike structure in the PABPC1-poly(A) complex, in which the PABPC1 molecules are linearly arrayed. NMR and cross-linking analyses indicate that PABPC1 forms a multimer by binding to the neighbouring PABPC1 molecules via interactions between the RNA recognition motif (RRM) 2 in one molecule and the middle portion of the linker region of another molecule. A PABPC1 mutant lacking the interaction site in the linker, which possesses an impaired ability to form the multimer, reduced the in vitro translation activity, suggesting the importance of PABPC1 multimer formation in the translation process. We therefore propose a model of the PABPC1 multimer that provides clues to comprehensively understand the regulation mechanism of mRNA translation.

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Papers, etc., Registered in KOARA 【 Display / hide

Reviews, Commentaries, etc. 【 Display / hide

  • Nuclear Magnetic Resonance Approaches for Characterizing Protein-Protein Interactions.

    Toyama Y, Mase Y, Kano H, Yokogawa Mariko, Osawa M, Shimada I

    Methods Mol Biol. 1684   115 - 128 2018.10

    Introduction and explanation (scientific journal), Joint Work

Research Projects of Competitive Funds, etc. 【 Display / hide

  • B型肝炎ウイルスの肝細胞侵入および増殖機構の構造生物学的解析


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 横川 真梨子, Grant-in-Aid for Scientific Research (C), Principal Investigator

  • Structural basis for hepatitis B virus infection


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 横川 真梨子, Grant-in-Aid for Young Scientists (B), Principal Investigator


Courses Taught 【 Display / hide











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Courses Previously Taught 【 Display / hide

  • 薬学基礎実習

    Keio University, 2015, Autumn Semester, Major subject, Laboratory work/practical work/exercise

  • C1(4)物質の変化

    Keio University, 2015, Autumn Semester, Lecture


  • 薬学実習IIA(化学、物理)

    Keio University, 2015, Spring Semester, Major subject, Laboratory work/practical work/exercise