a heart protein postulated to regulate the activity of the calcium pump of cardiac sarcoplasmic reticulum. A major substrate for the cAMP-dependent protein kinase. An inhibitor of cardiac muscle sarcoplasmic reticulum Ca(2+)-ATPase in the unphosphorylated state, but inhibition is relieved upon phosphorylation. The subsequent activation of the Ca(2+) pump leads to enhanced muscle relaxation rates, thereby contributing to the inotropic response elicited in heart by beta-agonists. A key regulator of cardiac diastolic function. Mutations are a cause of inherited human dilated cardiomyopathy with refractory congestive heart failure. Note: This description may include information from UniProtKB.
Protein type: Inhibitor; Membrane protein, integral
Cellular Component: endoplasmic reticulum; membrane; mitochondrion; perinuclear region of cytoplasm; sarcoplasmic reticulum membrane
Molecular Function: ATPase binding; ATPase inhibitor activity; enzyme inhibitor activity; identical protein binding; protein binding
Biological Process: cytosolic calcium ion homeostasis; negative regulation of ATPase activity; negative regulation of calcium ion transport; negative regulation of catalytic activity; negative regulation of heart rate; regulation of calcium ion transport; regulation of heart contraction; regulation of the force of heart contraction