Skip to main content
SpringerLink
Log in

Transporters Through the Looking Glass: An Insight into the Mechanisms of Ion-Coupled Transport and Methods That Help Reveal Them

  • Review Article
  • Published:
Journal of the Indian Institute of Science Aims and scope

Abstract

Cell membranes, despite providing a barrier to protect intracellular constituents, require selective gating for the influx of important metabolites including ions, sugars, amino acids, neurotransmitters and efflux of toxins and metabolic end-products. The machinery involved in carrying out this gating process comprises of integral membrane proteins that use ionic electrochemical gradients or ATP hydrolysis, to drive concentrative uptake or efflux. The mechanism through which ion-coupled transporters function is referred to as alternating-access. In the recent past, discrete modes of alternating-access have been described with the elucidation of new transporter structures and their snapshots in altered conformational states. Despite X-ray structures being the primary sources of mechanistic information, other biophysical methods provide information related to the structural dynamics of these transporters. Methods including EPR and smFRET, have extensively helped validate or clarify ion-coupled transport mechanisms, in a near-native environment. This review seeks to highlight the mechanistic details of ion-coupled transport and delve into the biophysical tools and methods that help in understanding these fascinating molecules.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Figure 1:
Figure 2:
Figure 3:
Figure 4:
Figure 5:
Figure 6:
Figure 7:

Similar content being viewed by others

References

  1. Abramson J, Smirnova I, Kasho V, Verner G, Kaback HR, Iwata S (2003) Structure and mechanism of the lactose permease of Escherichia coli. Science 301(5633):610–615. https://doi.org/10.1126/science.1088196

    Article  Google Scholar 

  2. Akyuz N, Altman RB, Blanchard SC, Boudker O (2013) Transport dynamics in a glutamate transporter homologue. Nature 502(7469):114–118. https://doi.org/10.1038/nature12265

    Article  Google Scholar 

  3. Akyuz N, Georgieva ER, Zhou Z, Stolzenberg S, Cuendet MA, Khelashvili G et al (2015) Transport domain unlocking sets the uptake rate of an aspartate transporter. Nature 518(7537):68–73. https://doi.org/10.1038/nature14158

    Article  Google Scholar 

  4. Barrera NP, Di Bartolo N, Booth PJ, Robinson CV (2008) Micelles protect membrane complexes from solution to vacuum. Science 321(5886):243–246. https://doi.org/10.1126/science.1159292

    Article  Google Scholar 

  5. Bibi E, Kaback HR (1990) In vivo expression of the lacY gene in two segments leads to functional lac permease. Proc Natl Acad Sci USA 87(11):4325–4329

    Article  Google Scholar 

  6. Bolla JR, Su CC, Delmar JA, Radhakrishnan A, Kumar N, Chou TH et al (2015) Crystal structure of the Alcanivorax borkumensis YdaH transporter reveals an unusual topology. Nat Commun 6:6874. https://doi.org/10.1038/ncomms7874

    Article  Google Scholar 

  7. Boudker O, Verdon G (2010) Structural perspectives on secondary active transporters. Trends Pharmacol Sci 31(9):418–426. https://doi.org/10.1016/j.tips.2010.06.004

    Article  Google Scholar 

  8. Caffrey M (2009) Crystallizing membrane proteins for structure determination: use of lipidic mesophases. Annu Rev Biophys 38:29–51. https://doi.org/10.1146/annurev.biophys.050708.133655

    Article  Google Scholar 

  9. Canul-Tec JC, Assal R, Cirri E, Legrand P, Brier S, Chamot-Rooke J et al (2017) Structure and allosteric inhibition of excitatory amino acid transporter 1. Nature 544(7651):446–451. https://doi.org/10.1038/nature22064

    Article  Google Scholar 

  10. Cesar-Razquin A, Snijder B, Frappier-Brinton T, Isserlin R, Gyimesi G, Bai X et al (2015) A call for systematic research on solute carriers. Cell 162(3):478–487. https://doi.org/10.1016/j.cell.2015.07.022

    Article  Google Scholar 

  11. Claxton DP, Quick M, Shi L, de Carvalho FD, Weinstein H, Javitch JA et al (2010) Ion/substrate-dependent conformational dynamics of a bacterial homolog of neurotransmitter:sodium symporters. Nat Struct Mol Biol 17(7):822–829. https://doi.org/10.1038/nsmb.1854

    Article  Google Scholar 

  12. Coleman JA, Green EM, Gouaux E (2016) X-ray structures and mechanism of the human serotonin transporter. Nature 532(7599):334–339. https://doi.org/10.1038/nature17629

    Article  Google Scholar 

  13. Damiano E, Bassilana M, Rigaud JL, Leblanc G (1984) Use of the pH sensitive fluorescence probe pyranine to monitor internal pH changes in Escherichia coli membrane vesicles. FEBS Lett 166(1):120–124

    Article  Google Scholar 

  14. Deng D, Xu C, Sun P, Wu J, Yan C, Hu M et al (2014) Crystal structure of the human glucose transporter GLUT1. Nature 510(7503):121–125. https://doi.org/10.1038/nature13306

    Article  Google Scholar 

  15. Drew D, Boudker O (2016) Shared molecular mechanisms of membrane transporters. Annu Rev Biochem 85:543–572. https://doi.org/10.1146/annurev-biochem-060815-014520

    Article  Google Scholar 

  16. Feng L, Campbell EB, Hsiung Y, MacKinnon R (2010) Structure of a eukaryotic CLC transporter defines an intermediate state in the transport cycle. Science 330(6004):635–641. https://doi.org/10.1126/science.1195230

    Article  Google Scholar 

  17. Feng L, Frommer WB (2015) Structure and function of SemiSWEET and SWEET sugar transporters. Trends Biochem Sci 40(8):480–486. https://doi.org/10.1016/j.tibs.2015.05.005

    Article  Google Scholar 

  18. Forrest LR, Zhang YW, Jacobs MT, Gesmonde J, Xie L, Honig BH et al (2008) Mechanism for alternating access in neurotransmitter transporters. Proc Natl Acad Sci USA 105(30):10338–10343. https://doi.org/10.1073/pnas.0804659105

    Article  Google Scholar 

  19. Fowler PW, Orwick-Rydmark M, Radestock S, Solcan N, Dijkman PM, Lyons JA et al (2015) Gating topology of the proton-coupled oligopeptide symporters. Structure 23(2):290–301. https://doi.org/10.1016/j.str.2014.12.012

    Article  Google Scholar 

  20. Futai M (1974) Orientation of membrane vesicles from Escherichia coli prepared by different procedures. J Membr Biol 15(1):15–28

    Article  Google Scholar 

  21. Gouaux E, Mackinnon R (2005) Principles of selective ion transport in channels and pumps. Science 310(5753):1461–1465. https://doi.org/10.1126/science.1113666

    Article  Google Scholar 

  22. Green EM, Coleman JA, Gouaux E (2015) Thermostabilization of the human serotonin transporter in an antidepressant-bound conformation. PLoS ONE 10(12):e0145688. https://doi.org/10.1371/journal.pone.0145688

    Article  Google Scholar 

  23. Gupta K, Donlan JAC, Hopper JTS, Uzdavinys P, Landreh M, Struwe WB et al (2017) The role of interfacial lipids in stabilizing membrane protein oligomers. Nature 541(7637):421–424. https://doi.org/10.1038/nature20820

    Article  Google Scholar 

  24. Hattori M, Hibbs RE, Gouaux E (2012) A fluorescence-detection size-exclusion chromatography-based thermostability assay for membrane protein precrystallization screening. Structure 20(8):1293–1299. https://doi.org/10.1016/j.str.2012.06.009

    Article  Google Scholar 

  25. Heng J, Zhao Y, Liu M, Liu Y, Fan J, Wang X et al (2015) Substrate-bound structure of the E. coli multidrug resistance transporter MdfA. Cell Res 25(9):1060–1073. https://doi.org/10.1038/cr.2015.94

    Article  Google Scholar 

  26. Hunte C, Michel H (2002) Crystallisation of membrane proteins mediated by antibody fragments. Curr Opin Struct Biol 12(4):503–508

    Article  Google Scholar 

  27. Jardetzky O (1966) Simple allosteric model for membrane pumps. Nature 211(5052):969–970

    Article  Google Scholar 

  28. Kawate T, Gouaux E (2006) Fluorescence-detection size-exclusion chromatography for precrystallization screening of integral membrane proteins. Structure 14(4):673–681. https://doi.org/10.1016/j.str.2006.01.013

    Article  Google Scholar 

  29. Kazmier K, Sharma S, Quick M, Islam SM, Roux B, Weinstein H et al (2014) Conformational dynamics of ligand-dependent alternating access in LeuT. Nat Struct Mol Biol 21(5):472–479. https://doi.org/10.1038/nsmb.2816

    Article  Google Scholar 

  30. Kermani AA, Macdonald CB, Gundepudi R, Stockbridge RB (2018) Guanidinium export is the primal function of SMR family transporters. Proc Natl Acad Sci USA 115(12):3060–3065. https://doi.org/10.1073/pnas.1719187115

    Article  Google Scholar 

  31. Koshy C, Schweikhard ES, Gartner RM, Perez C, Yildiz O, Ziegler C (2013) Structural evidence for functional lipid interactions in the betaine transporter BetP. EMBO J 32(23):3096–3105. https://doi.org/10.1038/emboj.2013.226

    Article  Google Scholar 

  32. Krishnamurthy H, Gouaux E (2012) X-ray structures of LeuT in substrate-free outward-open and apo inward-open states. Nature 481(7382):469–474. https://doi.org/10.1038/nature10737

    Article  Google Scholar 

  33. Krishnamurthy H, Piscitelli CL, Gouaux E (2009) Unlocking the molecular secrets of sodium-coupled transporters. Nature 459(7245):347–355. https://doi.org/10.1038/nature08143

    Article  Google Scholar 

  34. Kumar H, Kasho V, Smirnova I, Finer-Moore JS, Kaback HR, Stroud RM (2014) Structure of sugar-bound LacY. Proc Natl Acad Sci USA 111(5):1784–1788. https://doi.org/10.1073/pnas.1324141111

    Article  Google Scholar 

  35. Laganowsky A, Reading E, Hopper JT, Robinson CV (2013) Mass spectrometry of intact membrane protein complexes. Nat Protoc 8(4):639–651. https://doi.org/10.1038/nprot.2013.024

    Article  Google Scholar 

  36. Landau EM, Rosenbusch JP (1996) Lipidic cubic phases: a novel concept for the crystallization of membrane proteins. Proc Natl Acad Sci USA 93(25):14532–14535

    Article  Google Scholar 

  37. Lau FW, Nauli S, Zhou Y, Bowie JU (1999) Changing single side-chains can greatly enhance the resistance of a membrane protein to irreversible inactivation. J Mol Biol 290(2):559–564. https://doi.org/10.1006/jmbi.1999.2905

    Article  Google Scholar 

  38. Lee C, Yashiro S, Dotson DL, Uzdavinys P, Iwata S, Sansom MS et al (2014) Crystal structure of the sodium–proton antiporter NhaA dimer and new mechanistic insights. J Gen Physiol 144(6):529–544. https://doi.org/10.1085/jgp.201411219

    Article  Google Scholar 

  39. Lerner E, Cordes T, Ingargiola A, Alhadid Y, Chung S, Michalet X et al (2018) Toward dynamic structural biology: two decades of single-molecule Forster resonance energy transfer. Science 359(6373):eaan1133. https://doi.org/10.1126/science.aan1133

    Article  Google Scholar 

  40. Liu W, Wacker D, Wang C, Abola E, Cherezov V (2014) Femtosecond crystallography of membrane proteins in the lipidic cubic phase. Philos Trans R Soc Lond B Biol Sci 369(1647):20130314. https://doi.org/10.1098/rstb.2013.0314

    Article  Google Scholar 

  41. Ma D, Lu P, Shi Y (2013) Substrate selectivity of the acid-activated glutamate/gamma-aminobutyric acid (GABA) antiporter GadC from Escherichia coli. J Biol Chem 288(21):15148–15153. https://doi.org/10.1074/jbc.M113.474502

    Article  Google Scholar 

  42. Malinauskaite L, Quick M, Reinhard L, Lyons JA, Yano H, Javitch JA et al (2014) A mechanism for intracellular release of Na+ by neurotransmitter/sodium symporters. Nat Struct Mol Biol 21(11):1006–1012. https://doi.org/10.1038/nsmb.2894

    Article  Google Scholar 

  43. Mancusso R, Gregorio GG, Liu Q, Wang DN (2012) Structure and mechanism of a bacterial sodium-dependent dicarboxylate transporter. Nature 491(7425):622–626. https://doi.org/10.1038/nature11542

    Article  Google Scholar 

  44. Martens C, Stein RA, Masureel M, Roth A, Mishra S, Dawaliby R et al (2016) Lipids modulate the conformational dynamics of a secondary multidrug transporter. Nat Struct Mol Biol 23(8):744–751. https://doi.org/10.1038/nsmb.3262

    Article  Google Scholar 

  45. Masureel M, Martens C, Stein RA, Mishra S, Ruysschaert JM, McHaourab HS et al (2014) Protonation drives the conformational switch in the multidrug transporter LmrP. Nat Chem Biol 10(2):149–155. https://doi.org/10.1038/nchembio.1408

    Article  Google Scholar 

  46. McHaourab HS, Steed PR, Kazmier K (2011) Toward the fourth dimension of membrane protein structure: insight into dynamics from spin-labeling EPR spectroscopy. Structure 19(11):1549–1561. https://doi.org/10.1016/j.str.2011.10.009

    Article  Google Scholar 

  47. Michel H (1983) Crystallization of membrane proteins. [Review]. Trends Biochem Sci 8(2):5

    Article  Google Scholar 

  48. Misquitta LV, Misquitta Y, Cherezov V, Slattery O, Mohan JM, Hart D et al (2004) Membrane protein crystallization in lipidic mesophases with tailored bilayers. Structure 12(12):2113–2124. https://doi.org/10.1016/j.str.2004.09.020

    Article  Google Scholar 

  49. Mitchell P (1957) A general theory of membrane transport from studies of bacteria. Nature 180(4577):134–136

    Article  Google Scholar 

  50. Morales-Perez CL, Noviello CM, Hibbs RE (2016) Manipulation of subunit stoichiometry in heteromeric membrane proteins. Structure 24(5):797–805. https://doi.org/10.1016/j.str.2016.03.004

    Article  Google Scholar 

  51. Mulligan C, Fenollar-Ferrer C, Fitzgerald GA, Vergara-Jaque A, Kaufmann D, Li Y et al (2016) The bacterial dicarboxylate transporter VcINDY uses a two-domain elevator-type mechanism. Nat Struct Mol Biol 23(3):256–263. https://doi.org/10.1038/nsmb.3166

    Article  Google Scholar 

  52. Nasr ML, Singh SK (2014) Radioligand binding to nanodisc-reconstituted membrane transporters assessed by the scintillation proximity assay. Biochemistry 53(1):4–6. https://doi.org/10.1021/bi401412e

    Article  Google Scholar 

  53. Newstead S, Drew D, Cameron AD, Postis VL, Xia X, Fowler PW et al (2011) Crystal structure of a prokaryotic homologue of the mammalian oligopeptide-proton symporters, PepT1 and PepT2. EMBO J 30(2):417–426. https://doi.org/10.1038/emboj.2010.309

    Article  Google Scholar 

  54. Nomura N, Verdon G, Kang HJ, Shimamura T, Nomura Y, Sonoda Y et al (2015) Structure and mechanism of the mammalian fructose transporter GLUT5. Nature 526(7573):397–401. https://doi.org/10.1038/nature14909

    Article  Google Scholar 

  55. Penmatsa A, Wang KH, Gouaux E (2013) X-ray structure of dopamine transporter elucidates antidepressant mechanism. Nature 503(7474):85–90. https://doi.org/10.1038/nature12533

    Article  Google Scholar 

  56. Pos KM (2009) Drug transport mechanism of the AcrB efflux pump. Biochim Biophys Acta 1794(5):782–793. https://doi.org/10.1016/j.bbapap.2008.12.015

    Article  Google Scholar 

  57. Quick M, Javitch JA (2007) Monitoring the function of membrane transport proteins in detergent-solubilized form. Proc Natl Acad Sci USA 104(9):3603–3608. https://doi.org/10.1073/pnas.0609573104

    Article  Google Scholar 

  58. Quistgaard EM, Low C, Guettou F, Nordlund P (2016) Understanding transport by the major facilitator superfamily (MFS): structures pave the way. Nat Rev Mol Cell Biol 17(2):123–132. https://doi.org/10.1038/nrm.2015.25

    Article  Google Scholar 

  59. Radchenko M, Symersky J, Nie R, Lu M (2015) Structural basis for the blockade of MATE multidrug efflux pumps. Nat Commun 6:7995. https://doi.org/10.1038/ncomms8995

    Article  Google Scholar 

  60. Reddy VS, Shlykov MA, Castillo R, Sun EI, Saier MH Jr (2012) The major facilitator superfamily (MFS) revisited. FEBS J 279(11):2022–2035. https://doi.org/10.1111/j.1742-4658.2012.08588.x

    Article  Google Scholar 

  61. Reyes N, Ginter C, Boudker O (2009) Transport mechanism of a bacterial homologue of glutamate transporters. Nature 462(7275):880–885. https://doi.org/10.1038/nature08616

    Article  Google Scholar 

  62. Saier MH Jr, Tran CV, Barabote RD (2006) TCDB: the transporter classification database for membrane transport protein analyses and information. Nucleic Acids Res 34(Database issue):D181–D186. https://doi.org/10.1093/nar/gkj001

    Article  Google Scholar 

  63. Schuldiner S (2009) EmrE, a model for studying evolution and mechanism of ion-coupled transporters. Biochim Biophys Acta 1794(5):748–762. https://doi.org/10.1016/j.bbapap.2008.12.018

    Article  Google Scholar 

  64. Serrano-Vega MJ, Magnani F, Shibata Y, Tate CG (2008) Conformational thermostabilization of the beta1-adrenergic receptor in a detergent-resistant form. Proc Natl Acad Sci USA 105(3):877–882. https://doi.org/10.1073/pnas.0711253105

    Article  Google Scholar 

  65. Shaffer PL, Goehring A, Shankaranarayanan A, Gouaux E (2009) Structure and mechanism of a Na+-independent amino acid transporter. Science 325(5943):1010–1014. https://doi.org/10.1126/science.1176088

    Article  Google Scholar 

  66. Shi Y (2013) Common folds and transport mechanisms of secondary active transporters. Annu Rev Biophys 42:51–72. https://doi.org/10.1146/annurev-biophys-083012-130429

    Article  Google Scholar 

  67. Singh SK (2008) LeuT: a prokaryotic stepping stone on the way to a eukaryotic neurotransmitter transporter structure. Channels (Austin) 2(5):380–389

    Article  Google Scholar 

  68. Singh SK, Piscitelli CL, Yamashita A, Gouaux E (2008) A competitive inhibitor traps LeuT in an open-to-out conformation. Science 322(5908):1655–1661. https://doi.org/10.1126/science.1166777

    Article  Google Scholar 

  69. Smirnova I, Kasho V, Choe JY, Altenbach C, Hubbell WL, Kaback HR (2007) Sugar binding induces an outward facing conformation of LacY. Proc Natl Acad Sci USA 104(42):16504–16509. https://doi.org/10.1073/pnas.0708258104

    Article  Google Scholar 

  70. Sun L, Zeng X, Yan C, Sun X, Gong X, Rao Y et al (2012) Crystal structure of a bacterial homologue of glucose transporters GLUT1-4. Nature 490(7420):361–366. https://doi.org/10.1038/nature11524

    Article  Google Scholar 

  71. Tao Y, Cheung LS, Li S, Eom JS, Chen LQ, Xu Y et al (2015) Structure of a eukaryotic SWEET transporter in a homotrimeric complex. Nature 527(7577):259–263. https://doi.org/10.1038/nature15391

    Article  Google Scholar 

  72. Ujwal R, Abramson J (2012) High-throughput crystallization of membrane proteins using the lipidic bicelle method. J Vis Exp 59:e3383. https://doi.org/10.3791/3383

    Google Scholar 

  73. Vaidehi N, Grisshammer R, Tate CG (2016) How can mutations thermostabilize G-protein-coupled receptors? Trends Pharmacol Sci 37(1):37–46. https://doi.org/10.1016/j.tips.2015.09.005

    Article  Google Scholar 

  74. Vinothkumar KR, Henderson R (2010) Structures of membrane proteins. Q Rev Biophys 43(1):65–158. https://doi.org/10.1017/S0033583510000041

    Article  Google Scholar 

  75. Vinothkumar KR, Henderson R (2016) Single particle electron cryomicroscopy: trends, issues and future perspective. Q Rev Biophys 49:e13. https://doi.org/10.1017/S0033583516000068

    Article  Google Scholar 

  76. von Heijne G (2006) Membrane-protein topology. Nat Rev Mol Cell Biol 7(12):909–918. https://doi.org/10.1038/nrm2063

    Article  Google Scholar 

  77. Wang H, Elferich J, Gouaux E (2012) Structures of LeuT in bicelles define conformation and substrate binding in a membrane-like context. Nat Struct Mol Biol 19(2):212–219. https://doi.org/10.1038/nsmb.2215

    Article  Google Scholar 

  78. Wang KH, Penmatsa A, Gouaux E (2015) Neurotransmitter and psychostimulant recognition by the dopamine transporter. Nature 521(7552):322–327. https://doi.org/10.1038/nature14431

    Article  Google Scholar 

  79. Wohlert D, Grotzinger MJ, Kuhlbrandt W, Yildiz O (2015) Mechanism of Na(+)-dependent citrate transport from the structure of an asymmetrical CitS dimer. eLife 4:e09375. https://doi.org/10.7554/eLife.09375

    Article  Google Scholar 

  80. Yamashita A, Singh SK, Kawate T, Jin Y, Gouaux E (2005) Crystal structure of a bacterial homologue of Na+/Cl− dependent neurotransmitter transporters. Nature 437(7056):215–223. https://doi.org/10.1038/nature03978

    Article  Google Scholar 

  81. Yan N (2015) Structural biology of the major facilitator superfamily transporters. Annu Rev Biophys 44:257–283. https://doi.org/10.1146/annurev-biophys-060414-033901

    Article  Google Scholar 

  82. Yernool D, Boudker O, Jin Y, Gouaux E (2004) Structure of a glutamate transporter homologue from Pyrococcus horikoshii. Nature 431(7010):811–818. https://doi.org/10.1038/nature03018

    Article  Google Scholar 

  83. Zeppelin T, Ladefoged LK, Sinning S, Periole X, Schiott B (2018) A direct interaction of cholesterol with the dopamine transporter prevents its out-to-inward transition. PLoS Comput Biol 14(1):e1005907. https://doi.org/10.1371/journal.pcbi.1005907

    Article  Google Scholar 

  84. Zhao Y, Terry D, Shi L, Weinstein H, Blanchard SC, Javitch JA (2010) Single-molecule dynamics of gating in a neurotransmitter transporter homologue. Nature 465(7295):188–193. https://doi.org/10.1038/nature09057

    Article  Google Scholar 

Download references

Acknowledgements

The authors would like to thank all members of the Penmatsa Lab for their feedback on the manuscript. PM is supported by the IISc-GATE fellowship. AP is an intermediate fellow of the DBT-Wellcome Trust India Alliance (IA/1/15/2/502063) and a recipient of the Innovative Young Biotechnologist Award (IYBA) (BT/09/IYBA/2015/13) from the Department of Biotechnology (DBT), India.

Author information

Authors and Affiliations

  1. Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India

    Puja Majumder, Aditya Kumar Mallela & Aravind Penmatsa

Authors
  1. Puja Majumder
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Aditya Kumar Mallela
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Aravind Penmatsa
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Aravind Penmatsa.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Majumder, P., Mallela, A.K. & Penmatsa, A. Transporters Through the Looking Glass: An Insight into the Mechanisms of Ion-Coupled Transport and Methods That Help Reveal Them. J Indian Inst Sci 98, 283–300 (2018). https://doi.org/10.1007/s41745-018-0081-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s41745-018-0081-5

Keywords

Search

Navigation