!Citation=Casagrande R, et al. (2000). Mol Cell 5 (4):729-35 !Title=Degradation of proteins from the ER of S. cerevisiae requires an intact unfolded protein response pathway. !PubMedID=10882108 !Name=Unfolded Protein Response !ExptSetNo=1576 !Description=To dissect the requirements of membrane protein degradation from the ER, we expressed the mouse major histocompatibility complex class I heavy chain H-2K(b) in yeast. Like other proteins degraded from the ER, unassembled H-2K(b) heavy chains are not transported to the Golgi but are degraded in a proteasome-dependent manner. The overexpression of H-2K(b) heavy chains induces the unfolded protein response (UPR). In yeast mutants unable to mount the UPR, H-2K(b) heavy chains are greatly stabilized. This defect in degradation is suppressed by the expression of the active form of Hac1p, the transcription factor that upregulates UPR-induced genes. These results indicate that induction of the UPR is required for the degradation of protein substrates from the ER.