Skip to main content
. 2021 Dec 24;12:808593. doi: 10.3389/fmicb.2021.808593

FIGURE 2.

FIGURE 2

Schematic diagram of coronavirus infection modulating the UPR arms. When misfolded proteins accumulate in the lumen of ER, chaperone binding immunoglobulin (BiP/GRP78) is separated from the lumen domains of the three ER sensors, allowing PERK and IRE1 to form a homodimer and activate the transport of ATF6 to the Golgi. All three branches of the UPR were induced in SARS-CoV-2, MHV, PEDV and TGEV infected cells. Individual over-expression of SARS-CoV and SARS-CoV-2 ORF8 protein is sufficient to induce the IRE1 and ATF6 pathway of UPR. While SARS-CoV-2 S protein activates all three branches of the UPR, SARS-CoV S protein only induces PERK pathway.