Where is rough endoplasmic reticulum located?

The rough endoplasmic reticulum (RER) is primarily located in the cytoplasm of eukaryotic cells. It is a series of membrane-bound structures that are continuous with the nuclear envelope, giving it a close association with the nucleus, but it is considered part of the cytoplasmic environment where it functions. The RER is called "rough" due to the presence of ribosomes on its cytoplasmic surface, which are responsible for the synthesis of proteins. These ribosomes attach to the RER when they are actively translating messenger RNA into proteins.

While ribosomes themselves are not a location, they play a crucial role in the function of the rough endoplasmic reticulum. The RER is involved in the production and processing of proteins that are either secreted from the cell, incorporated into the cell’s plasma membrane, or sent to an organelle. The nucleus serves as the control center for the cell where genetic material is housed, and the cell wall is a rigid structure outside of the plasma membrane found in plants, fungi, and some bacteria, but it does not pertain to the localization of the RER. Thus, the correct context of the rough endoplasmic reticulum’s location is within the cytoplasm