How do proteins translocate into the lumen of the rough endoplasmic reticulum?
What is different about the protein that is destined for the rough endoplasmic reticulum? [Note: This section describes work that led to a Nobel Prize in Medicine and Physiology to Dr. Gunter Blobel. For more information about Dr. Blobel’s work and the pioneering discoveries, click: http://www.nobel.se/medicine/laureates/1999/ ] The major difference is the fact that it has a hydrophobic signal sequence. This simplified cartoon shows that this is the first part of the protein produced. After the signal sequence is completed, protein synthesis is further inhibited. This is to allow the interaction of the signal sequence with a complex on the rough endoplasmic reticulum. In the above cartoon, note that the signal peptide is allowed to enter and essentially guide the protein into the lumen of the rough endoplasmic reticulum. Once the signal sequence is detected, protein synthesis resumes and the rest of the protein is inserted in the lumen. Note that a signal peptidase near the inner surfa
