PLB: 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.
Protein type: Inhibitor; Membrane protein, integral
Chromosomal Location of Human Ortholog: 10|10 B3
Cellular Component: endoplasmic reticulum; integral component of membrane; membrane; mitochondrion; protein complex; sarcoplasmic reticulum; sarcoplasmic reticulum membrane; vesicle
Molecular Function: ATPase inhibitor activity; calcium channel regulator activity; protein binding
Biological Process: adrenergic receptor signaling pathway involved in heart process; calcium ion transport; cardiac muscle tissue development; cellular calcium ion homeostasis; negative regulation of heart contraction; Notch signaling pathway; protein homooligomerization; regulation of calcium ion import; regulation of cardiac muscle cell contraction; regulation of cardiac muscle contraction by regulation of the release of sequestered calcium ion; regulation of heart contraction; regulation of relaxation of muscle; regulation of release of sequestered calcium ion into cytosol by sarcoplasmic reticulum; regulation of the force of heart contraction; regulation of the force of heart contraction by cardiac conduction; response to testosterone stimulus; response to zinc ion
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