Is the endoplasmic reticulum involved in protein synthesis?

Yes, protein synthesis is one of the key functions of the endoplasmic reticulum. Protein synthesis occurs in the ribosomes that are attached to the membrane of the rough endoplasmic reticulum (rough ER).

The code for making proteins is contained in messenger RNA (mRNA) molecules in the nucleus. The mRNA moves from the nucleus to a ribosome on the rough ER’s surface where it gets synthesized into protein. The rough ER processes and packages the newly synthesized proteins and transports them in vesicles to the cell membrane or to other organelles such as the Golgi apparatus. Some of these proteins will be utilized by the cell while others will be sent out into intercellular space.