Interaction of DWORF with SERCA and PLB as determined by EPR spectroscopy.

Insufficient sarco/endoplasmic reticulum calcium ATPase (SERCA) activity significantly contributes to heart failure, which is a leading cause of death worldwide. A characteristic pathology of cardiac disease is the slow and incomplete Ca removal from the myocyte cytoplasm in diastole, which is primarily driven by SERCA, the integral transmembrane Ca pump. Phospholamban (PLB) allosterically inhibits SERCA by reducing its apparent Ca affinity.