<prompt> The function of Phospholamban isRegulates Na K pumpTransports calcium out of the mitrochondriaBinds actin with myosinInhibits Ca pump on sarcoplasmic reticulum  <response>: Phospholamban inhibits calcium pump on sarcoplasmic reticulum, thereby preventing uptake of Ca from the sarcoplasm. When it is phosphorylated, the Ca channels open up and uptake of Ca is increased into the sarcoplasmic reticulum. 