Phospholamban stoichiometry in canine cardiac muscle sarcoplasmic reticulum.
Treatment of cardiac sarcoplasmic reticulum with the crosslinking reagent dithiobis (succinimidyl propionate) in the presence of 125I-calmodulin, resulted in the formation of a 40,000-dalton affinity labeled component, consisting of a 1:1, phospholamban: 125I-calmodulin complex. In parallel experiments, sarcoplasmic reticulum was phosphorylated in the presence of calmodulin and [gamma-32P]ATP, and then treated with the crosslinking reagent to produce an affinity labeled component consisting of a 1:1, calmodulin: 32P-phospholamban complex. These experiments permitted determination of the amount of 125I and 32P incorporated into the 40,000-dalton complexes, as well as the amount of 32P incorporated into the 23,000-dalton form of phospholamban. If 1 mol of Ca2+-dependent ATPase phosphoprotein represents 1 mol of 100,000-dalton Ca2+-dependent ATPase monomer, then there are 4.88 +/- 1.33 mol Ca2+-dependent ATPase/mol of phospholamban. If there are 2 mol of Ca2+-dependent ATPase phosphoprotein/mol of 100,000-dalton Ca2+-dependent ATPase monomer, then there are 9.76 +/- 2.66 mol Ca2+-dependent ATPase/mol phospholamban.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D004285:Dogs; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D012519:Sarcoplasmic Reticulum / Q000201:enzymology / Q000378:metabolism*; D000099211:Phospholamban
D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D000099211:Phospholamban