The unfolded protein response is a stress response in the ER. This stress pathway results in a halt to global protein synthesis and the activation of translation of factors required to respond to the stress inducer. Which of the following proteins of translation is the primary target of the ER stress response?
A) eIF-2
B) eIF2B
C) eIF-4E
D) eEF-1α
E) eEF-2

Question

Quizplus · Accepted Answer

The primary target of the ER stress response is eIF-2, which gets phosphorylated, leading to a reduction in global protein synthesis while allowing the translation of specific stress response proteins. Proteins that are destined for secretory vesicles are translated while associated with endoplasmic reticulum (ER) membranes. During translation secreted proteins are transported into the lumen of the ER in an unfolded state. Proper folding occurs prior to the transfer of the protein to the Golgi apparatus. Accumulation of unfolded proteins triggers the unfolded protein response (UPR) which is a form of ER stress. Among the proteins activated by the UPR is an eIF-2α kinase termed PERK (RNA-dependent protein kinase [PKR]-like ER kinase). The aim of PERK-mediated phosphorylation of eIF-2α is to reduce global protein synthesis allowing the cell time to correct the impaired process of protein folding.

The Unfolded Protein Response Is a Stress Response in the ER