<prompt> Phospholamban is a protein leads toThat increase interaction of calcium with myofilamentsThat leads to sequestration of calcium in endoplasmic reticulumThat leads to sequestration of calcium by mitochondriaThat activates CaNa pump  <response>: That leads to sequestration of Ca2 in endoplasmic reticulum Phospholamban is a protein contained within the sarcoplasmic reticulum that inhibits the activity of the sarcoplasmic calcium pump. Inactivation of the phospholamban results in an increase in calcium sequestration by the SR. In cardiac muscle, the rapid sequestration of Ca2 shoens the duration of the contraction. In smooth muscle, sequestration causes the muscles to relax. Phospholamban has little effect on skeletal muscle contraction. 