Eukaryotic initiation factor 2B: identification of multiple phosphorylation sites in the epsilon-subunit and their functions in vivo.
Eukaryotic initiation factor (eIF) 2B is a heteromeric guanine nucleotide exchange factor that plays an important role in regulating mRNA translation. Here we identify multiple phosphorylation sites in the largest, catalytic, subunit (epsilon) of mammalian eIF2B. These sites are phosphorylated by four different protein kinases. Two conserved sites (Ser712/713) are phosphorylated by casein kinase 2. They lie at the extreme C-terminus and are required for the interaction of eIF2Bepsilon with its substrate, eIF2, in vivo and for eIF2B activity in vitro. Glycogen synthase kinase 3 (GSK3) is responsible for phosphorylating Ser535. This regulatory phosphorylation event requires both the fourth site (Ser539) and a distal region, which acts to recruit GSK3 to eIF2Bepsilon in vivo. The fifth site, which lies outside the catalytic domain of eIF2Bepsilon, can be phosphorylated by casein kinase 1. All five sites are phosphorylated in the eIF2B complex in vivo.
Wang
X
X
Division of Molecular Physiology, School of Life Sciences and MRC Protein Phosphorylation Unit, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, UK.
Paulin
F E
FE
Campbell
L E
LE
Gomez
E
E
O'Brien
K
K
Morrice
N
N
Proud
C G
CG
D000818:Animals; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D047390:Casein Kinase II; D002460:Cell Line; D020717:Eukaryotic Initiation Factor-2B / Q000235:genetics / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D020717:Eukaryotic Initiation Factor-2B; D011993:Recombinant Fusion Proteins; D038341:Glycogen Synthase Kinases; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3