The endoplasmic reticulum

The endoplasmic reticulum (ER) is a multi-functional organelle vital for the proper functioning of a cell. It consists of the rough ER (rER), which serves as a site for the synthesis, folding, and transport of proteins, and the smooth ER (sER), which is heavily involved in the biogenesis of lipids and steroids. When folded correctly, a protein’s cellular function occurs normally; however, the accumulation of unfolded or incorrectly folded proteins during stressed conditions in the ER leads to the instigation of the unfolded protein response (UPR). This aims to protect the cell from a cellular stress response known as ER stress, which coordinates adaptive and apoptotic responses in order to restore and maintain ER homeostasis. The pathogenesis of disease states such as neurodegenerative diseases, metabolic disorders, type II diabetes, and inflammatory diseases, however, have also been linked to prolonged and persistent ER stress.