Proteins are translated and modified with in the rough endoplasmic reticulum. In order to complete their modifications, they are transported in membrane-bounded vesicles to the cis side of the Golgi apparatus.

Transport vesicles from the rough ER fuse together and become the cis cisterna of the Golgi.

Once they reach the Golgi apparatus, additional modifications are made to the transported proteins by resident Golgi enzymes. These modifications are key in ensuring the proteins reach their final destinations once they leave the Golgi apparatus.

The Golgi apparatus is divided into distinct regions. These include the cis cisterna, nearest the ER, the centrally located medial cisternae, the trans cisterna, and the trans Golgi Network (TGN).