All these organelles are involved in protein synthesis and transport.
First, proteins are assembled on ribosomes. Proteins targeted for export to the cell membrane complete their assembly on ribosomes attached to the endoplasmic reticulum. Then, the newly assembled proteins are carried from the rough ER to the Golgi apparatus in vesicles. The Golgi apparatus further processes and packages the proteins produced in the rough ER and secrete them to other parts of the cell or to the cell surface for export.
