Table 1.
ER stress regulators and their functions.
| Yeast (Sc) | Mammal (Hs) | Plant (At) | Functional annotation | References |
|---|---|---|---|---|
| IRE1 | IRE1 | IRE1a/b | ER membrane–associated RNA splicing factor. In plants, IRE1b plays a major role. ER stress activates IRE1, which promotes the splicing of a pre-mRNA. IRE1 responses are delayed with respect to ATF6 responses. |
Ron and Walter, 2007 Hetz and Glimcher, 2009 Liu et al., 2012 Koizumi et al., 2001 |
| HAC1 | XBP1 | bZIP60 | A bZIP transcription factor binds to ERSEs. IRE1 splices mRNA encoding XBP1/Hac1/bZIP60 upon ER stress activation. |
Cox and Walter, 1996 Yoshida et al., 2001 Deng et al., 2011 |
| *N.I. | ATF6 | bZIP17, bZIP28 | An ER type II transmembrane protein associated with the binding protein BiP/GRP78 under normal conditions but activated and trafficked to Golgi for splicing in response to ER stress. |
Liu et al., 2007 Iwata and Koizumi, 2012 |
| *N.I. | PERK | *N.I. | dsRNA-activated protein kinase-like ER kinase. | Hetz, 2012 |
| *N.I. | eIF2α | *N.I. | Phosphorylation of the eukaryotic translation initiation factor 2 a-subunit (eIF2α) by PERK upon ER stress downregulates protein synthesis. | Vattem and Wek, 2004 |
| *N.I. | ATF4 | *N.I. | Transcriptional factor, activated by upstream PERK–eIF2α to induce ER stress apoptosis. |
Sc, Saccharomyces cerevisiae; Hs, Homo sapiens; At, Arabidopsis thaliana; IRE1, inositol-requiring enzyme; ER, endoplasmic reticulum; ATF, activating transcription factor; XBP1, X-box binding protein 1; bZIP, basic leucine zipper; ERSEs, ER stress elements; BiP, binding protein; GRP78, 78 kDa glucose regulated protein; PERK, protein kinase R-like endoplasmic reticulum kinase; eIF2α, eukaryotic translation initiation factor 2 a-subunit. *N.I., not identified.