The endoplasmic reticulum is the principal site of secretory and membrane protein folding, and disturbances in its homeostasis trigger the unfolded protein response (UPR), an adaptive signaling network that restores folding capacity or, if stress is unresolved, commits the cell to death. ER stress is sensed by three transmembrane transducers whose activity is restrained by the abundant chaperone BiP/GRP78. As misfolded proteins accumulate, BiP is titrated away, releasing and activating these sensors. PERK, a protein kinase, dimerizes and phosphorylates the translation initiation factor eIF2alpha; the resulting Phospho-eIF2alpha attenuates global cap-dependent translation to reduce client protein load while paradoxically permitting preferential translation of ATF4, a transcription factor that induces genes for amino acid metabolism, redox balance, and, under prolonged stress, the proapoptotic factor CHOP/DDIT3. A second arm is governed by IRE1alpha, an endoribonuclease that splices XBP1 messenger RNA to produce a potent transcriptional activator of chaperones and ER-associated degradation components. Together these branches expand folding capacity, enhance protein quality control, and clear terminally misfolded substrates. When the imbalance persists, sustained CHOP expression and other death signals tip the response toward apoptosis. Chronic UPR activation underlies metabolic diseases including diabetes and hepatic steatosis, neurodegeneration, and the survival of secretory cancers within stressful tumor microenvironments, while pharmacological modulation of these sensors is being pursued therapeutically. Monitoring BiP/GRP78, PERK, eIF2alpha and its phosphorylation, ATF4, CHOP/DDIT3, IRE1alpha, and XBP1 together provides a panoramic view of how cells perceive folding stress and decide between adaptation and demise. This pack brings together validated antibodies against these central targets to support detailed dissection of ER stress and the unfolded protein response.
![Anti-IRE1 [ARC57190] Monoclonal Antibody (CAB21021)](https://cdn11.bigcommerce.com/s-39x6lpnvxv/images/stencil/1280x1280/products/237958/281378/er-stress-upr-antibody-sampler-pack__53889__31622.1786234283.jpg?c=1&imbypass=on "Anti-IRE1 [ARC57190] Monoclonal Antibody (CAB21021)")
![Anti-IRE1 [ARC57190] Monoclonal Antibody (CAB21021)](https://cdn11.bigcommerce.com/s-39x6lpnvxv/images/stencil/100x100/products/237958/281378/er-stress-upr-antibody-sampler-pack__53889__31622.1786234283.jpg?c=1 "Anti-IRE1 [ARC57190] Monoclonal Antibody (CAB21021)")
