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How does the Golgi apparatus send proteins to the cell membrane?

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Diagram of the Golgi apparatus showing its stacked, curved membranes with labeled parts including cisternae, cis face, trans face, lumen, and various vesicles involved in cellular transport and secretion. — Golgi apparatus A membrane-bound organelle of eukaryotic cells, the Golgi apparatus is made up of a series of flattened, stacked pouches called cisternae that function as a series of compartments that progressively refine and direct cellular products to their proper destinations. .

The Golgi apparatus facilitates the delivery of proteins to the cell membrane through a highly organized process of modification, sorting, and packaging.12

After proteins are synthesized in the endoplasmic reticulum, they enter the Golgi apparatus at the cis face. As they progress through the organelle's distinct compartments—the cis, medial, and trans cisternae—they undergo chemical modifications, such as the addition or removal of sugar groups or phosphorylation, which are essential for their stability, activity, and proper targeting.23

In the final stage, proteins are sorted within the trans Golgi network and packaged into specialized vesicles at the trans face. These vesicles then transport the molecules to their designated destinations, including the cell membrane. Once they reach the membrane, some proteins are delivered for integration, while others are released into the extracellular environment through a process known as exocytosis.2