Phospho-EIF2S1 (Ser51) Recombinant Rabbit mAb (S-3036)

Phospho-EIF2S1 (Ser51) is the phosphorylated form of eukaryotic translation initiation factor 2 alpha (eIF2α) at its 51st serine residue, catalyzed by four stress-sensing kinases (PERK, GCN2, PKR, and HRI) in response to various cellular stress signals. This phosphorylation serves as the central molecular switch of the integrated stress response (ISR): phosphorylated eIF2α increases its affinity for eIF2B, competitively inhibiting the GDP-GTP exchange cycle of the eIF2 complex, thereby leading to a rapid decrease in global protein synthesis rates and reducing the burden of nascent proteins on the endoplasmic reticulum. Simultaneously, this translational inhibition selectively promotes the translation of specific stress-related mRNAs (such as that encoding the transcription factor ATF4) that contain upstream open reading frames (uORFs), activating an adaptive transcriptional program to help cells restore homeostasis. Precise regulation of Phospho-EIF2S1 (Ser51) levels is crucial in physiological and pathological processes: in neurodegenerative diseases (such as Alzheimer's disease and Parkinson's disease), chronic endoplasmic reticulum stress leads to sustained eIF2α phosphorylation, which enhances aberrant translation of synaptic plasticity-related proteins and promotes tau protein hyperphosphorylation, accelerating disease progression. In tumors, cancer cells exploit the eIF2α phosphorylation mechanism to resist endoplasmic reticulum stress and chemotherapy-induced apoptosis, thereby gaining a survival advantage. In viral infections, PKR-mediated eIF2α phosphorylation restricts viral replication by shutting down the host cell translation system, becoming a key component of antiviral innate immunity. Furthermore, Phospho-EIF2S1 (Ser51) is an important pharmacological target for studying cellular stress responses, and blocking its downstream effects with specific inhibitors (such as ISRIB) has shown therapeutic potential in various disease models. In summary, as a central node in translational regulation and stress adaptation, Phospho-EIF2S1 (Ser51) profoundly influences cell fate determination and disease development through dynamic modulation of protein synthesis rates and gene expression programs.