Cells have extensive sets of intracellular membranes, which together compose the endomembrane system. The endomembrane system was first discovered in the late 1800s when scientist Camillo Golgi ...

The endoplasmic reticulum (ER) is the portion of the cell responsible for manufacturing and folding proteins. Proteins are essential for a wide range of cellular functions—as enzymes ...

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.