| Definition: |
A stress-inducible protein catabolic pathway that promotes protein quality control by accelerating the degradation of misfolded ER membrane and cytosolic proteins, as well as native proteins. The pathway starts with the activation, by stress, of the Nma111p/Ynm3p serine protease, which cleaves the stress-induced hydrophilin Roq1p, resulting in the generation of a Roq1p cleavage product that selectively interacts with Ubr1p, an E3 ubiquitin ligase. Interaction with the Ubr1p type-1 substrate binding site reprograms the substrate specificity of this ubiquitin ligase resulting in the selective proteasome-mediated degradation of misfolded and native proteins. The pathway ends with degradation of the protein by the cytoplasmic proteasome. Currently, NMA111, ROQ1, UBR1, RAD6, and CDC48 are considered to be involved in this quality control pathway. |