Catalytic domain of the Serine/Threonine kinase, eukaryotic translation Initiation Factor 2-Alpha Kinase 3 or PKR-like Endoplasmic Reticulum Kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PERK (or EIF2AK3) is a type-I ER transmembrane protein containing a luminal domain bound with the chaperone BiP under unstressed conditions and a cytoplasmic catalytic kinase domain. In response to the accumulation of misfolded or unfolded proteins in the ER, PERK is activated through the release of BiP, allowing it to dimerize and autophosphorylate. It functions as the central regulator of translational control during the Unfolded Protein Response (UPR) pathway. In addition to the eIF-2 alpha subunit, PERK also phosphorylates Nrf2, a leucine zipper transcription factor which regulates cellular redox status and promotes cell survival during the UPR. EIF2AKs phosphorylate the alpha subunit of eIF-2, resulting in the downregulation of protein synthesis. The PERK 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.",