The primary function of SERCA pumps is to transport Ca²⁺ ions from the cytosol into the sarcoplasmic and endoplasmic reticulum. This process is essential for muscle relaxation after contraction. The pump operates by hydrolyzing ATP to provide the energy necessary for moving Ca²⁺ against its concentration gradient. Each cycle of the pump moves two Ca²⁺ ions into the lumen of the reticulum and exchanges them for two or three protons.
