1. Structural Biology and Molecular Biophysics
  2. Biochemistry and Chemical Biology
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Structural mechanism of ligand activation in human calcium-sensing receptor

  1. Yong Geng
  2. Lidia Mosyak
  3. Igor Kurinov
  4. Hao Zuo
  5. Emmanuel Sturchler
  6. Tat Cheung Cheng
  7. Prakash Subramanyam
  8. Alice P Brown
  9. Sarah C Brennan
  10. Hee-chang Mun
  11. Martin Bush
  12. Yan Chen
  13. Trang X Nguyen
  14. Baohua Cao
  15. Donald D Chang
  16. Matthias Quick
  17. Arthur D Conigrave
  18. Henry M Colecraft
  19. Patricia McDonald
  20. Qing R Fan  Is a corresponding author
  1. Columbia University, United States
  2. Cornell University, United States
  3. The Scripps Translational Science Institute, United States
  4. University of Sydney, Australia
Research Article
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Cite this article as: eLife 2016;5:e13662 doi: 10.7554/eLife.13662

Abstract

Human calcium-sensing receptor (CaSR) is a G-protein coupled receptor (GPCR) that maintains extracellular Ca2+ homeostasis through the regulation of parathyroid hormone secretion. It functions as a disulfide-tethered homodimer composed of three main domains, the Venus Flytrap module, cysteine-rich domain, and seven-helix transmembrane region. Here we present the crystal structures of the entire extracellular domain of CaSR in the resting and active conformations. We provide direct evidence that L-amino acids are agonists of the receptor. In the active structure, L-Trp occupies the orthosteric agonist-binding site at the interdomain cleft, and is primarily responsible for inducing extracellular domain closure to initiate receptor activation. Our structures reveal multiple binding sites for Ca2+ and PO43- ions. Both ions are crucial for structural integrity of the receptor. While Ca2+ ions stabilize the active state, PO43- ions reinforce the inactive conformation. The activation mechanism of CaSR involves the formation of a novel dimer interface between subunits.

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Author details

  1. Yong Geng

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Lidia Mosyak

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Igor Kurinov

    Department of Chemistry and Chemical Biology, Cornell University, Ithaca, United States
    Competing interests
    The authors declare that no competing interests exist.

  4. Hao Zuo

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Emmanuel Sturchler

    Department of Molecular Therapeutics, The Scripps Translational Science Institute, Jupiter, United States
    Competing interests
    The authors declare that no competing interests exist.

  6. Tat Cheung Cheng

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  7. Prakash Subramanyam

    Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  8. Alice P Brown

    School of Life and Environmental Sciences, University of Sydney, New South Wales, Australia
    Competing interests
    The authors declare that no competing interests exist.

  9. Sarah C Brennan

    School of Life and Environmental Sciences, University of Sydney, New South Wales, Australia
    Competing interests
    The authors declare that no competing interests exist.

  10. Hee-chang Mun

    School of Life and Environmental Sciences, University of Sydney, New South Wales, Australia
    Competing interests
    The authors declare that no competing interests exist.

  11. Martin Bush

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  12. Yan Chen

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  13. Trang X Nguyen

    Department of Psychiatry, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  14. Baohua Cao

    Department of Pharmacology, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  15. Donald D Chang

    Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  16. Matthias Quick

    Department of Psychiatry, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  17. Arthur D Conigrave

    School of Life and Environmental Sciences, University of Sydney, New South Wales, Australia
    Competing interests
    The authors declare that no competing interests exist.

  18. Henry M Colecraft

    Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  19. Patricia McDonald

    Department of Molecular Therapeutics, The Scripps Translational Science Institute, Jupiter, United States
    Competing interests
    The authors declare that no competing interests exist.

  20. Qing R Fan

    Department of Pharmacology, Columbia University, New York, United States
    For correspondence
    qf13@cumc.columbia.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9330-0963

Funding

National Institute of General Medical Sciences (R01GM112973)

  • Qing R Fan

American Heart Association (15GRNT25420002)

  • Qing R Fan

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

Reviewing Editor

  1. Ehud Y Isacoff, University of California, Berkeley, United States

Publication history

  1. Received: December 9, 2015
  2. Accepted: July 18, 2016
  3. Accepted Manuscript published: July 19, 2016 (version 1)
  4. Version of Record published: August 8, 2016 (version 2)

Copyright

© 2016, Geng 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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