Catalytic domain of the Serine/Threonine kinase, eukaryotic translation Initiation Factor 2-Alpha Kinase 2 or Protein Kinase regulated by RNA
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PKR (or EIF2AK2) contains an N-terminal double-stranded RNA (dsRNA) binding domain and a C-terminal catalytic kinase domain. It is activated by dsRNA, which is produced as a replication intermediate in virally infected cells. It plays a key role in mediating innate immune responses to viral infection. PKR is also directly activated by PACT (protein activator of PKR) and heparin, and is inhibited by viral proteins and RNAs. PKR also regulates transcription and signal transduction in diseased cells, playing roles in tumorigenesis and neurodegenerative diseases. EIF2AKs phosphorylate the alpha subunit of eIF-2, resulting in the downregulation of protein synthesis. The PKR subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
Jiyao W et al.(2023). "The conserved domain database in 2023.",