Phospholamban is a protein leads to

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.