EIF2AK2/PKR
PKR is an interferon-induced, double-stranded RNA-activated kinase encoded by EIF2AK2 that operates as a cytoplasmic pattern-recognition sensor in antiviral defense. Binding of dsRNA to its two N-terminal dsRNA-binding domains relieves autoinhibition and promotes dimer-dependent autophosphorylation. Activated PKR phosphorylates Ser51 of eIF2α, shutting down cap-dependent translation and thereby restricting viral replication, while also feeding into NF-κB and apoptosis pathways. PKR responds to cellular stress beyond infection, including proteotoxic and genotoxic signals, and is dysregulated in cancer and neurodegeneration. Recombinant PKR is widely used to study innate immune signaling, translational control, and small molecules that modulate the dsRNA response.
