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 protein; Membrane protein, integral
Cellular Component: sarcoplasmic reticulum membrane; membrane; mitochondrion; endoplasmic reticulum; perinuclear region of cytoplasm; mitochondrial membrane; vesicle
Molecular Function: enzyme inhibitor activity; identical protein binding; protein binding; ATPase inhibitor activity; calcium channel regulator activity; ATPase binding
Biological Process: cardiac muscle development; negative regulation of calcium ion transport; cytosolic calcium ion homeostasis; negative regulation of heart rate; blood circulation; response to testosterone stimulus; regulation of calcium ion transport; regulation of heart contraction; response to zinc ion; calcium ion transport; negative regulation of catalytic activity; negative regulation of ATPase activity; protein homooligomerization; regulation of the force of heart contraction
SS: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.