This HTRF kit enables the cell-based quantitative detection of phosphorylated Phospholamban at Ser16..This cell-based assay enables the detection of Phosphorylated Phospholamban (PLN) at Serine 16. The phospho assay along with the total PLN assay are ideal for monitoring the activation of PKA in response GPCR stimulation, such as the beta2 Adrenergic receptor. PKA phosphorylates PLN at the Ser 16 residue. In an unphosphorylated state, PLN inhibits SERCA2a which is the Ca2+ pump controling the contractility of the cardiac muscle. PLN phosphorylation induced by PKA and CaMKII, on Ser16 and Thr17 sites respectively, abrogates SERCA2a inhibition. The PLN phosphorylation state regulates the activity of this Ca2+ pump in the heart..