Thomas Ostwald and David MacLennan were characterizing proteins that bind to calcium in the sarcoplasmic reticulum — a specialized type of endoplasmic reticulum found in muscle cells.
Sarco/endoplasmic reticulum Ca 2+-ATPase (SERCA): An enzyme that pumps calcium ions from the cytoplasm into the sarcoplasmic reticulum, crucial for muscle relaxation. Sodium-potassium ATPase (NKA ...