HRI and DELE1. Dele1/HRI signals to shut down translation when mit import fails and aggregates are accumulating. SIFI complex only targets active DELE1/HRI for ubiuqitylation. Ubr ko active DELE1 stable.

When does this happen in cells? Atf4 TF readout of cell stress. DeltaUbr4 - cell has a lot of trouble cleaning up after stress. Signals need to be actively turned off. Timing? Amphipathic helices are degrons that interact with Ubr4. Mitochondrial pre-sequences also!