What is the main role of the rough endoplasmic reticulum?

The main role of the rough endoplasmic reticulum (RER) is protein synthesis. The rough endoplasmic reticulum is studded with ribosomes on its cytoplasmic surface, which gives it a "rough" appearance under a microscope. These ribosomes are the sites where the synthesis of proteins occurs. As proteins are made, they are usually threaded into the lumen of the RER, where they undergo folding and modifications necessary for their proper function.

Once the proteins are synthesized and processed, the RER can package them into vesicles for transport to other parts of the cell, such as the Golgi apparatus, where further modification and sorting can take place before they are sent to their final destinations. This vital role in the production and initial processing of proteins distinguishes the rough endoplasmic reticulum from other organelles involved in different cellular functions.

The rough endoplasmic reticulum does not primarily participate in detoxification, lipid synthesis, or the storage of genetic material, which are roles associated with different cellular structures and processes.