protein synthesized by ribosomes on the RER are translocated into the internal compartment of the ER. These protein may be used at a distant location within the cell or secreted from the cell. They are transported within vesicles that bud off the RER. These transport vesicles tra vel to the cis face of the Golgi apparatus. There they can be modified and packaged into vesicles that bud off the trans face of the Golgi apparatus. Vesicles leaving the trans face transport proteins to other location in the cell, or fuse with the plasma membrane, releasing their contents to the extracellular environment. within