Characterization of junctate-SERCA2a interaction in murine cardiomyocyte.
Junctate is a newly identified sarcoplasmic reticulum (SR) Ca(2+) binding protein, but its function in cardiac muscle has remained unclear. Our previous study showed that chronic over-expression of junctate in transgenic mice led to altered SR functions and development of severe hypertrophy. In this study, we identified the interaction of junctate with SERCA2a by co-immunoprecipitation and GST-pull-down assay. This interaction was inhibited by higher Ca(2+) concentration. Immunolocalization assays also showed that junctate and SERCA2a were co-localized in the SR of cardiomyocytes. Direct binding of the C-terminal region of junctate (amino acids 79-270) and luminal domain of SERCA2a (amino acids 70-89) was observed by deletion mutation experiments. Adenovirus-mediated transient over-expression of junctate in cardiomyocytes showed a reduced decay time of Ca(2+) transients and increased oxalate-supported SERCA2 Ca(2+) uptake, suggesting an increased activity of SERCA2a. Taken together, according to our data, junctate may play an important role in the regulation of SR Ca(2+) cycling through the interaction with SERCA2a in the murine heart.
Kwon
Soon-Jae
SJ
Department of Life Science and Systems Biology Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.
Kim
Do Han
DH
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000201:enzymology*; D054730:Protein Interaction Domains and Motifs; D051381:Rats; D017207:Rats, Sprague-Dawley; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; C498841:Asph protein, mouse; D006899:Mixed Function Oxygenases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506947:Atp2a2 protein, mouse; D002118:Calcium