Abstract 1534 Identification of ERAD-dependent degrons for the endoplasmic reticulum lumen

Over one-third of all proteins pass through the endoplasmic reticulum (ER) and must undergo folding events to reach their native state. Protein folding is an error-prone process, and misfolded proteins can be removed from the ER lumen and membrane by ER-associated degradation (ERAD). Hrd1 is a ubiquitin ligase that is a central component in ERAD of lumenal and transmembrane proteins in all eukaryotes. However, the sequences allowing recognition by Hrd1 (called degrons) are largely unidentified. Degrons are commonly short, linear sequences of amino acids that are sufficient for targeting proteins for degradation. We have identified the first groups of degrons that function within the ER through Hrd1-mediated ERAD, followed by degradation by the cytosolic proteasome. These degrons were identified through screening penta-amino acid libraries in S. cerevisiae and validated in both S. cerevisiae and mammalian cell lines. We demonstrate that the N-terminal degrons function for both soluble lumenal and integral ER membrane proteins and provide useful tools for driving degradation from the ER lumen. J.D. was supported by the NIH Pharmacological Sciences Training Grant (T32-GM140223). R.S. (previously R. Plumb) was supported by an NIH/NIGMS Award (5F32GM136020) and D.D. was supported by the NIH Cellular and Molecular Biology Training Grant (T32-GM007315). In addition, this work was supported by an NIH/NIGMS Award (R35GM128592 to R.D.B.).