In muscle cells, SERCA pumps are crucial for muscle relaxation. After a muscle contraction, Ca²⁺ must be rapidly removed from the cytosol to allow the muscle to relax. SERCA pumps actively transport Ca²⁺ back into the sarcoplasmic reticulum, thus lowering cytosolic calcium levels and enabling muscle relaxation. Malfunctioning SERCA pumps can lead to conditions like [hypercontractility]() and muscle fatigue.
