The endomembrane system is composed of a number of inter-related membrane sacs within the cytoplasm of the cell.
The endomembrane system functions, in part, in
protein sorting and
Proteins that are synthesized on the rough endoplasmic reticulum are those that will be secreted, found in lysosomes, found in peroxisomes, found in microbodies or will become integral membrane proteins .
Proteins are transported from the endoplasmic reticulum to the golgi apparatus and from the golgi apparatus to the plasma membrane in transport vesicles.
An example of the flow of proteins is shown in the following animation. To learn more about the different components of the endomembrane system click on the names above.