During cellular stress the protein folding capacity of the ER is diminished. In order to maintain homeostasis and ensure proper protein folding cells activate the unfolded protein response (UPR), a signaling network consisting of sensors and effectors to enhance the chaperone activity of the cell, increase degradation of accumulated proteins, and/or trigger apoptosis. Inositol-requiring enzyme 1 (IRE1), an ER-transmembrane protein, is an essential component of the UPR pathway important for sensing and responding to ER stress.
