Table 1 Comparison summary of the UPR in yeast, mammals, and plants
From: Comparison and contrast of plant, yeast, and mammalian ER stress and UPR
UPR arms | Yeast | Mammal | Plant |
|---|---|---|---|
IRE1-mediated mRNA splicing of HAC1, XBP1, and bZIP60 | HAC1 spliced by IRE1p binds to UPRE to upregulate UPR gene expression Spliced HAC1 is longer than unspliced HAC1 | XBP1 spliced by IRE1α binds to UPRE or ERSE-I to upregulate UPR gene expression Spliced XBP1 is longer than unspliced XBP1 | bZIP60 splicing by IRE1 binds to UPRE or ERSE to upregulate UPR gene expression Spliced bZIP60 is shorter than unspliced bZIP60 |
Proteolytic activation of ATF6, bZIP28, and bZIP17 by S1P and S2P | – | ATF6 cleaved by S1P and S2P at Golgi binds to ERSE-I or ERSE-II together with NF-Y | bZIP28 and bZIP17 cleavage by S1P and S2P at the Golgi bZIP28 translocates to the nucleus and binds to ERSE-I to upregulate UPR gene expression |
PERK-mediated phosphorylation of elF2α and translational control | – | eIF2α phosphorylated by PERK decreases global protein translation to reduce ER unfolded protein load and control translation of UPR genes. ATF4 activated by phosphorylated eIF2α binds to AARE to upregulate CHOP | – |