QUESTION: Endoplasmic reticulum and proteins – What is the unfolded protein response?
Sometimes the Endoplasmic Reticulum’s (ER) machinery can become overwhelmed with unfolded proteins. This can result from the overproduction of proteins or from errors in the oligosaccharide processing steps that guide the ER’s quality control operations. If the cell doesn’t effectively deal with the stress on the machinery, the result would be devastating.
When strained in this way, the cell can respond with a form of feedback regulation called the unfolded protein response (UPR). When too many unfolded proteins are present in the ER, protein synthesis at the rough ER slows down and mRNA molecules that specify the production of proteins processed through the ER are degraded.
The unfolded protein response represents another instance of the elegant molecular logic that permeates life’s biochemistry. It also bespeaks foresight and planning -- indicators of intelligent design.