Figure 4.

Infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) may cause ER stress, inducing an adaptive response known as the UPR. SARS-CoV-2 infects ACE2-expressing cells. BiP on the cell surface may increase infectability as observed in Middle East respiratory syndrome coronavirus (MERS-CoV) infection. Mature viral proteins are transported from the ER to the ER-Golgi intermediate compartment (ERGIC), where viral particles are assembled from these proteins as well as nucleocapsid proteins, RNA, and lipid membranes. The replication of viral proteins causes ER stress, which is tolerated by the cell because of the UPR. Unstable proteins such as GPCRs, like olfactory receptors and taste receptors, may be susceptible to ERAD.