Preservation of the in VivoPhosphorylation Status of Phospholamban in the Heart: Evidence for a Site-Specific Difference in the Dephosphorylation of Phospholamban (original) (raw)

The phosphorylation status of the cardiac sarcoplasis removed and SR Ca 2/ uptake is increased (1). In mic reticular (SR) protein phospholamban determines vivo, phosphorylation takes place at Ser 16 and Thr 17 by the activity of the SR Ca 2/ -ATPase. In order to predict cAMP-dependent protein kinase and Ca 2/ /calmodulin-SR Ca 2/ transport in vivo, it is vital that techniques dependent protein kinase respectively (2). Endogenous used to measure the phosphorylation status of phosphosphatases act to reverse the action of these kinases pholamban adequately clamp the endogenous kinases (3). The phosphorylation status of phospholamban is and phosphatases which modify phosphorylation durmodified primarily by b-adrenergic stimulation, which ing sample preparation. A recent study (Boateng, S., increases phosphorylation at both sites , but changes Seymour, A-M., Dunn, M., Yacoub, M., and Boheler, K. in phosphorylation have also been observed in patho-(1997) Biochem. Biophys. Res. Comm. 239, 701-705) has