In eukaryotic cells, the endoplasmic reticulum (ER) and the Golgi apparatus are part of an elaborate network of membrane compartments called the endomembrane system. These organelles work together to make and process many of the proteins, lipids, and carbohydrates that the cell uses or exports. The subset of cellular proteins that begin their journeys in the ER are those that will be exported from the cell, incorporated into membranes, or moved into organelles of the endomembrane system, such as lysosomes. In this animation, we examine the path of some of these proteins, from their production in the ER, to their transport through the Golgi, to their release from the cell.
Proteins that begin life in the endoplasmic reticulum (ER) follow a path from this organelle through each compartment of the Golgi apparatus to their final destinations. En route, the proteins are chemically modified by enzymes within the ER and Golgi. Enzymes in the ER attach sugars to the proteins, and enzymes in the Golgi compartments add or remove sugars, resulting in the formation of mature glycoproteins. Both organelles are required to produce mature proteins, which are then targeted via transport vesicles to their correct location within or outside the cell.
Textbook Reference: Concept 4.3 Eukaryotic Cells Have a Nucleus and Other Membrane-Bound Compartments