SERCA, or Sarco/Endoplasmic Reticulum Ca2+-ATPase,'s a calcium ATPase type P-ATPase. Function SERCA resides in the sarcoplasmic reticulum (SR) within muscle cells. It's a Ca2+ ATPase which transfers Ca2+ from the cytosol of the cell to the lumen of the SR at the expense of ATP hydrolysis during muscle relaxation. There're 3 major domains on the cytoplasmic face of SERCA: the phosphorylation and nucleotide-binding domains form the catalytic site, whereas the actuator domain's involved in the tran… (More on Serca)