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Title 

Role of junctin protein interactions in cellular dynamics of calsequestrin polymer upon calcium perturbation

Authors 

K W LeeJ S MaengJung Yi ChoiY R LeeChae Young HwangSung Sup ParkHyun Kyu ParkBong Hyun ChungSeung Goo LeeY S KimH JeonS H EomC H KangD H KimKi Sun Kwon

Publisher 

American Society for Biochemistry and Molecular Biology

Issue Date 

2012

Citation 

Journal of Biological Chemistry, vol. 287, no. 13, pp. 1679-1687

Abstract 

Calsequestrin (CSQ), the major intrasarcoplasmic reticulum calcium storage protein, undergoes dynamic polymerization and depolymerization in a Ca 2+-dependent manner. However, no direct evidence of CSQ depolymerization in vivo with physiological relevance has been obtained. In the present study, live cell imaging analysis facilitated characterization of the in vivo dynamics of the macromolecular CSQ structure. CSQ2 appeared as speckles in the presence of normal sarcoplasmic reticulum (SR) Ca 2+ that were decondensed upon Ca 2+ depletion. Moreover, CSQ2 decondensation occurred only in the stoichiometric presence of junctin (JNT). When expressed alone, CSQ2 speckles remained unchanged, even after Ca 2+ depletion. FRET analysis revealed constant interactions between CSQ2 and JNT, regardless of the SR Ca 2+ concentration, implying that JNT is an essential component of the CSQ scaffold. In vitro solubility assay, electron microscopy, and atomic force microscopy studies using purified recombinant proteins confirmed Ca 2+and JNT-dependent disassembly of the CSQ2 polymer. Accordingly, we conclude that reversible polymerization and depolymerization of CSQ are critical in SR Ca 2+ homeostasis.

ISSN 

0021-9258

Link 

http://dx.doi.org/10.1074/jbc.M111.254045

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2019-05-02


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