Final answer:
The synthesis of proteins on the RER involves ribosomes transferring newly synthesized proteins into the RER lumen for modification. The RER also produces phospholipids for cellular membranes. Integral membrane proteins have specific signal sequences that guide them to the RER.
Step-by-step explanation:
The synthesis of proteins on the rough endoplasmic reticulum (RER) involves several steps. Firstly, ribosomes transfer newly synthesized proteins into the lumen of the RER, where they undergo structural modifications such as folding or addition of side chains. These modified proteins are then incorporated into cellular membranes or secreted from the cell. Additionally, the RER also produces phospholipids for cellular membranes.
Integral membrane proteins have specific signal sequences that guide ribosomes to the RER. The proteins are trapped in the membrane by stop-transfer sequences, resulting in the formation of membrane-spanning proteins.
Overall, the RER plays a crucial role in synthesizing, modifying, and transporting proteins within the cell.