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Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response

JP2 (junctophilin-2) is believed to hold the transverse tubular and jSR (junctional sarcoplasmic reticulum) membranes in a precise geometry that facilitates excitation–contraction coupling in cardiomyocytes. We have expressed and purified human JP2 and shown using electron microscopy that the protei...

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Autores principales: Bennett, Hayley J., Davenport, John Bernard, Collins, Richard F., Trafford, Andrew W., Pinali, Christian, Kitmitto, Ashraf
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Portland Press Ltd. 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898329/
https://www.ncbi.nlm.nih.gov/pubmed/24001019
http://dx.doi.org/10.1042/BJ20130591
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author Bennett, Hayley J.
Davenport, John Bernard
Collins, Richard F.
Trafford, Andrew W.
Pinali, Christian
Kitmitto, Ashraf
author_facet Bennett, Hayley J.
Davenport, John Bernard
Collins, Richard F.
Trafford, Andrew W.
Pinali, Christian
Kitmitto, Ashraf
author_sort Bennett, Hayley J.
collection PubMed
description JP2 (junctophilin-2) is believed to hold the transverse tubular and jSR (junctional sarcoplasmic reticulum) membranes in a precise geometry that facilitates excitation–contraction coupling in cardiomyocytes. We have expressed and purified human JP2 and shown using electron microscopy that the protein forms elongated structures ~15 nm long and 2 nm wide. Employing lipid-binding assays and quartz crystal microbalance with dissipation we have determined that JP2 is selective for PS (phosphatidylserine), with a K(d) value of ~0.5 μM, with the N-terminal domain mediating this interaction. JP2 also binds PtdIns(3,4,5)P(3) at a different site than PS, resulting in the protein adopting a more flexible conformation; this interaction is modulated by both Ca(2+) and Mg(2+) ions. We show that the S101R mutation identified in patients with hypertrophic cardiomyopathy leads to modification of the protein secondary structure, forming a more flexible molecule with an increased affinity for PS, but does not undergo a structural transition in response to binding PtdIns(3,4,5)P(3). In conclusion, the present study provides new insights into the structural and lipid-binding properties of JP2 and how the S101R mutation may have an effect upon the stability of the dyad organization with the potential to alter JP2–protein interactions regulating Ca(2+) cycling.
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spelling pubmed-38983292014-01-23 Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response Bennett, Hayley J. Davenport, John Bernard Collins, Richard F. Trafford, Andrew W. Pinali, Christian Kitmitto, Ashraf Biochem J Research Article JP2 (junctophilin-2) is believed to hold the transverse tubular and jSR (junctional sarcoplasmic reticulum) membranes in a precise geometry that facilitates excitation–contraction coupling in cardiomyocytes. We have expressed and purified human JP2 and shown using electron microscopy that the protein forms elongated structures ~15 nm long and 2 nm wide. Employing lipid-binding assays and quartz crystal microbalance with dissipation we have determined that JP2 is selective for PS (phosphatidylserine), with a K(d) value of ~0.5 μM, with the N-terminal domain mediating this interaction. JP2 also binds PtdIns(3,4,5)P(3) at a different site than PS, resulting in the protein adopting a more flexible conformation; this interaction is modulated by both Ca(2+) and Mg(2+) ions. We show that the S101R mutation identified in patients with hypertrophic cardiomyopathy leads to modification of the protein secondary structure, forming a more flexible molecule with an increased affinity for PS, but does not undergo a structural transition in response to binding PtdIns(3,4,5)P(3). In conclusion, the present study provides new insights into the structural and lipid-binding properties of JP2 and how the S101R mutation may have an effect upon the stability of the dyad organization with the potential to alter JP2–protein interactions regulating Ca(2+) cycling. Portland Press Ltd. 2013-11-08 2013-12-01 /pmc/articles/PMC3898329/ /pubmed/24001019 http://dx.doi.org/10.1042/BJ20130591 Text en © 2013 The author(s) has paid for this article to be freely available under the terms of the Creative Commons Attribution Licence (CC-BY)(http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. http://creativecommons.org/licenses/by/3.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Bennett, Hayley J.
Davenport, John Bernard
Collins, Richard F.
Trafford, Andrew W.
Pinali, Christian
Kitmitto, Ashraf
Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response
title Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response
title_full Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response
title_fullStr Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response
title_full_unstemmed Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response
title_short Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P(3) and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response
title_sort human junctophilin-2 undergoes a structural rearrangement upon binding ptdins(3,4,5)p(3) and the s101r mutation identified in hypertrophic cardiomyopathy obviates this response
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898329/
https://www.ncbi.nlm.nih.gov/pubmed/24001019
http://dx.doi.org/10.1042/BJ20130591
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