TY - JOUR
T1 - Identification and characterization of pancreatic eukaryotic initiation factor 2 α-subunit kinase, PEK, involved in translational control
AU - Shi, Yuguang
AU - Vattem, Krishna M.
AU - Sood, Ruchira
AU - An, Jie
AU - Liang, Jingdong
AU - Stramm, Lawrence
AU - Wek, Ronald C.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1998/12
Y1 - 1998/12
N2 - In response to various environmental stresses, eukaryotic cells down- regulate protein synthesis by phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (elF-2α). In mammals, the phosphorylation was shown to be carried out by elF-2α kinases PKR and HRI. We report the identification and characterization of a cDNA from rat pancreatic islet cells that encodes a new related kinase, which we term pancreatic eIF-2α kinase, or PEK. In addition to a catalytic domain with sequence and structural features conserved among eIF2α kinases, PEK contains a distinctive amino- terminal region 550 residues in length. Using recombinant PEK produced in Escherichia coli or Sf-9 insect cells, we demonstrate that PEK is autophosphorylated on both serine and threonine residues and that the recombinant enzyme can specifically phosphorylate elF-2α on Serine-51. Northern blot analyses indicate that PEK mRNA is expressed in all tissues examined, with highest levels in pancreas cells. Consistent with our mRNA assays, PEK activity was predominantly detected in pancreas and pancreatic islet cells. The regulatory role of PEK in protein synthesis was demonstrated both in vitro and in vivo. The addition of recombinant PEK to reticulocyte lysates caused a dose-dependent inhibition of translation. In the Saccharomyces model system, PEK functionally substituted for the endogenous yeast elF-2α kinase, GCN2, by a process requiring the serine-51 phosphorylation site in elF-2α. We also identified PEK homologs from both Caenorhabditis elegans and the puffer fish Fugu rubripes, suggesting that this elF-2α kinase plays an important role in translational control from nematodes to mammals.
AB - In response to various environmental stresses, eukaryotic cells down- regulate protein synthesis by phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (elF-2α). In mammals, the phosphorylation was shown to be carried out by elF-2α kinases PKR and HRI. We report the identification and characterization of a cDNA from rat pancreatic islet cells that encodes a new related kinase, which we term pancreatic eIF-2α kinase, or PEK. In addition to a catalytic domain with sequence and structural features conserved among eIF2α kinases, PEK contains a distinctive amino- terminal region 550 residues in length. Using recombinant PEK produced in Escherichia coli or Sf-9 insect cells, we demonstrate that PEK is autophosphorylated on both serine and threonine residues and that the recombinant enzyme can specifically phosphorylate elF-2α on Serine-51. Northern blot analyses indicate that PEK mRNA is expressed in all tissues examined, with highest levels in pancreas cells. Consistent with our mRNA assays, PEK activity was predominantly detected in pancreas and pancreatic islet cells. The regulatory role of PEK in protein synthesis was demonstrated both in vitro and in vivo. The addition of recombinant PEK to reticulocyte lysates caused a dose-dependent inhibition of translation. In the Saccharomyces model system, PEK functionally substituted for the endogenous yeast elF-2α kinase, GCN2, by a process requiring the serine-51 phosphorylation site in elF-2α. We also identified PEK homologs from both Caenorhabditis elegans and the puffer fish Fugu rubripes, suggesting that this elF-2α kinase plays an important role in translational control from nematodes to mammals.
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U2 - 10.1128/mcb.18.12.7499
DO - 10.1128/mcb.18.12.7499
M3 - Article
C2 - 9819435
AN - SCOPUS:0031755020
VL - 18
SP - 7499
EP - 7509
JO - Molecular and Cellular Biology
JF - Molecular and Cellular Biology
SN - 0270-7306
IS - 12
ER -