Final answer:
The rough endoplasmic reticulum (RER) plays a role in sorting proteins that are destined for the cell membrane.
Step-by-step explanation:
The rough endoplasmic reticulum (RER) plays a role in sorting proteins that are destined for the cell membrane. The RER is covered with ribosomes that synthesize proteins, and these proteins are then transported from the ER in small sacs called transport vesicles. The RER works with the Golgi apparatus to move new proteins to their proper destinations in the cell.