Anti-eIF2a (phospho S51) Antibody - Identical to Abcam (ab131505) and Novus (NB100-81896)

The Antibodies.com polyclonal antibody specifically recognizes eukaryotic Initiation Factor 2 alpha (eIF2α) when the critical Serine 51 residue is phosphorylated. Phosphorylation of eIF2α at S51 is the central molecular switch of the integrated stress response (ISR), driven by four upstream kinases: PERK, GCN2, HRI, and PKR. This modification stalls translational initiation by blocking eIF2B-mediated guanine nucleotide exchange, redirecting cellular resources toward stress adaptation or, when prolonged, toward apoptosis.

Supplied as 50 µL of unconjugated rabbit IgG, this reagent is validated for Western blot, immunohistochemistry, and immunofluorescence workflows across human, mouse, and rat samples. The phospho-specific recognition enables researchers to monitor UPR activation, ER stress signaling, and downstream ISR effectors such as ATF4 and CHOP in neurodegeneration models, metabolic disease studies, viral infection research, and oncology investigations. The polyclonal format provides signal across multiple epitopes surrounding the phospho-S51 site, useful for tracking dynamic or modest changes in phosphorylation status.

Recommended storage at -20°C in working aliquots helps preserve antibody activity and limit freeze-thaw damage across multiple experimental sessions. The unconjugated format allows flexible pairing with user-preferred secondary reagents and fluorescent labels for multiplexed imaging or quantitative Western blot detection.