Mutations in the NKXD consensus element indicate that GTP binds to the gamma-subunit of translation initiation factor eIF2.
Initiation factor eIF2 binds GTP and promotes the binding of methionyl-tRNA to ribosomes. Biochemical and sequence evidence suggests that the GTP might bind to either the beta- or gamma-subunit of eIF2. Mutations were made in the NKXD consensus elements found in both subunits and individual mutant forms were overexpressed in transiently transfected COS-1 cells. The effect on the translational efficiency of a reporter mRNA for dihydrofolate reductase was monitored. Mutations in the gamma-subunit cause severe repression of protein synthesis, whereas those in the beta-subunit are only mildly inhibitory. The results support the view that GTP binds exclusively to the gamma-subunit.
Naranda
T
T
Department of Biological Chemistry, School of Medicine, University of California, Davis 95616, USA.
Sirangelo
I
I
Fabbri
B J
BJ
Hershey
J W
JW
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D039881:Prokaryotic Initiation Factor-2; D012333:RNA, Messenger / Q000032:analysis; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis
D010448:Peptide Initiation Factors; D039881:Prokaryotic Initiation Factor-2; D012333:RNA, Messenger; D006160:Guanosine Triphosphate; D013762:Tetrahydrofolate Dehydrogenase