Final answer:
PERK is activated as part of the unfolded protein response in cells, leading to the reduction of protein synthesis to alleviate stress on the endoplasmic reticulum.
Step-by-step explanation:
When PERK is activated, it has a critical function in the cell's response to stress, particularly in the endoplasmic reticulum (ER). Protein Kinase R (PKR)-like Endoplasmic Reticulum Kinase (PERK) is one of the principal sensors of the unfolded protein response (UPR), a cellular mechanism that is triggered by the presence of misfolded or an excess of normal proteins in the ER. The activation of PERK leads to the phosphorylation and inactivation of the eukaryotic initiation factor 2 (eIF2α), which, in turn, reduces the overall rate of protein synthesis within the cell. This mechanism helps to alleviate stress on the ER by slowing down new protein production and allowing time for the recovery of proper protein folding capabilities.