Cardiac Calcium ATPase Dimerization Measured by Cross-Linking and Fluorescence Energy Transfer Journal Article

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Authors: Blackwell, D. J.; Zak, T. J.; Robia, S. L.
Article Title: Cardiac Calcium ATPase Dimerization Measured by Cross-Linking and Fluorescence Energy Transfer
Abstract: The cardiac sarco/endoplasmic reticulum calcium ATPase (SERCA) establishes the intracellular calcium gradient across the sarcoplasmic reticulum membrane. It has been proposed that SERCA forms homooligomers that increase the catalytic rate of calcium transport. We investigated SERCA dimerization in rabbit left ventricular myocytes using a photoactivatable cross-linker. Western blotting of cross-linked SERCA revealed higher-molecular-weight species consistent with SERCA oligomerization. Fluorescence resonance energy transfer measurements in cells transiently transfected with fluorescently labeled SERCA2a revealed that SERCA readily forms homodimers. These dimers formed in the absence or presence of the SERCA regulatory partner, phospholamban (PLB) and were unaltered by PLB phosphorylation or changes in calcium or ATP. Fluorescence lifetime data are compatible with a model in which PLB interacts with a SERCA homodimer in a stoichiometry of 1:2. Together, these results suggest that SERCA forms constitutive homodimers in live cells and that dimer formation is not modulated by SERCA conformational poise, PLB binding, or PLB phosphorylation.
Journal Title: Biophysical journal
Volume: 111
Issue: 6
ISSN: 1542-0086; 0006-3495
Publisher: Unknown  
Journal Place: United States
Date Published: 2016
Start Page: 1192
End Page: 1202
Language: ENG
DOI/URL:

10.1016/j.bpj.2016.08.005
Notes: LR: 20161019; CI: Copyright (c) 2016; GR: R01 HL092321/HL/NHLBI NIH HHS/United States; GR: R01 HL106189/HL/NHLBI NIH HHS/United States; JID: 0370626; PMCR: 2017/09/20; 2016/02/28 [received]; 2016/07/13 [revised]; 2016/08/01 [accepted]; ppublish