The endomembrane system is a series of compartments that work together to package, label, and ship proteins and molecules. In your cells, the endomembrane system is made up of both the endoplasmic reticulum and the Golgi apparatus. These compartments are folds of membranes that form tubes and sacs in your cells. Lysosomes are part of the endomembrane system, and some vesicles that leave the Golgi are bound for the lysosome. Most of the proteins found in the membrane of a lysosome have an unusually large number of carbohydrate—sugar—groups attached to them.
