Cells respond to an accumulation of unfolded proteins in the endoplasmic re
ticulum (ER) by increasing transcription of genes encoding ER resident prot
eins. The information is transmitted from the ER lumen to the nucleus by an
intracellular signaling pathway called the unfolded protein response (UPR)
. Recent work has shown that this signaling pathway utilizes several novel
mechanisms, including translational attenuation and a regulated mRNA splici
ng step. In this review we aim to integrate these recent advances with curr
ent knowledge about maintenance of ER composition and abundance.