Reconstitution of phospholamban--an approach to its function.
Isolated cardiac Ca,Mg-dependent ATPase of the sarcoplasmic reticulum and purified phospholamban, a proteolipid involved in the regulation of the calcium transport systems of the heart muscle, were reconstituted into soybean lecithin liposomes. Whereas the enzymatic activity of the CaATPase in the obtained liposomes was unaffected as well as by unphosphorylated and cAMP-dependent phosphorylated phospholamban, the capacity of oxalate-supported calcium uptake was lowered in the presence of phospholamban. The proteolipid is discussed not as a regulatory protein of the enzyme but as a mediator of the calcium storage in the lumen of the liposomes or sarcoplasmic reticulum network.
D000818:Animals; D001693:Biological Transport, Active; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000493:pharmacokinetics; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D066298:In Vitro Techniques; D008081:Liposomes; D009206:Myocardium / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013552:Swine; D000099211:Phospholamban
D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D008081:Liposomes; D000099211:Phospholamban