ABSTRACT
Eukaryotic cells are highly organized and contain a number of membrane-bound compartments that each serve specialized functions. In order to perform these functions, each organelle contains a unique set of membrane-bound and soluble molecules. Since most macromolecules are synthesized at one location but reside in another, mechanisms must exist for transporting them from their sites of synthesis to their final destinations. In the case of the endomembrane system, transport of membrane proteins and lipids from their sites of synthesis (usually the endoplasmic reticulum (ER) and Golgi apparatus) occurs via the exocytic pathway, and internalization occurs via the endocytic pathway.
