1. Structural Biology and Molecular Biophysics
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Handling of intracellular K+ determines voltage dependence of plasmalemmal monoamine transporter function

  1. Shreyas Bhat
  2. Marco Niello
  3. Klaus Schicker
  4. Christian Pifl
  5. Harald H Sitte
  6. Michael Freissmuth
  7. Walter Sandtner  Is a corresponding author
  1. Medical University of Vienna, Austria
  2. University of Vienna, Austria
Research Article
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Cite this article as: eLife 2021;10:e67996 doi: 10.7554/eLife.67996

Abstract

The concentrative power of the transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT) is thought to be fueled by the transmembrane Na+ gradient, but it is conceivable that they can also tap other energy sources, e.g. membrane voltage and/or the transmembrane K+ gradient. We address this by recording uptake of endogenous substrates or the fluorescent substrate APP+ ((4-(4-dimethylamino)phenyl-1-methylpyridinium) under voltage control in cells expressing DAT, NET or SERT. We show that DAT and NET differ from SERT in intracellular handling of K+. In DAT and NET, substrate uptake was voltage-dependent due to the transient nature of intracellular K+ binding, which precluded K+ antiport. SERT, however, antiports K+ and achieves voltage-independent transport. Thus, there is a trade-off between maintaining constant uptake and harvesting membrane potential for concentrative power, which we conclude to occur due to subtle differences in the kinetics of co-substrate ion binding in closely related transporters.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2,3,5,6 in the following DOI published by dryad. https://doi.org/10.5061/dryad.6q573n5z8

Article and author information

Author details

  1. Shreyas Bhat

    Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7019-9180
  2. Marco Niello

    Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  3. Klaus Schicker

    2Division of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  4. Christian Pifl

    University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  5. Harald H Sitte

    Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1339-7444
  6. Michael Freissmuth

    Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  7. Walter Sandtner

    Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
    For correspondence
    walter.sandtner@meduniwien.ac.at
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3637-260X

Funding

Austrian Science Fund (P 31599)

  • Walter Sandtner

Austrian Science Fund (P 31813)

  • Walter Sandtner

Austrian Science Fund (W1232)

  • Harald H Sitte

Vienna Science and Technology Fund (CS15-033)

  • Harald H Sitte

Vienna Science and Technology Fund (LS17-026)

  • Michael Freissmuth

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Christof Grewer, Binghamton University, United States

Publication history

  1. Received: March 1, 2021
  2. Accepted: May 30, 2021
  3. Accepted Manuscript published: June 1, 2021 (version 1)
  4. Version of Record published: June 10, 2021 (version 2)

Copyright

© 2021, Bhat et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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