Other components of the ubiquitin-proteasome system were also recruited to polysomes during infection, including HSPA5/BiP (the ER-resident Hsp70) and DNAJC3/Erdj6, which facilitate co-translational degradation of polypeptides on the ER (reviewed in [16]); and TRIM25, an E3 ligase of the antiviral ISG15 conjugation system, which targets nascent viral proteins [17] (S2 Fig). Here, ISG15 is linked to infection.