Mutations in the NKXD consensus element indicate that GTP binds to the γ‐subunit of translation initiation factor eIF2

Abstract

~,bstract Initiation factor elF2 binds GTP and promotes the binding of methionyl-tRNA to ribosomes. Biochemical and sequence evidence suggests that the GTP might bind to either the /3-or 3,-subunit of elF2. 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 y-subunit cause severe repression of protein synthesis, whereas those in the/]-subunit are only mildly inhibitory. The results support the view that GTP binds exclusively to the 3,-subunit.

TALEN-Mediated Gene Disruption on Y Chromosome Reveals Critical Role of EIF2S3Y in Mouse Spermatogenesis

“…Eif2s3y encodes the g-subunit of eIF-2, which forms a ternary complex with GTP and Met-tRNA and then binds to the small (40S) ribosomal subunit, which participates in translational initiation [30]. eIF-2 is composed of three subunits: a, b, and g. The g-subunit contains binding domains for GTP and Met-tRNA [31][32][33].…”

GTP-dependent Recognition of the Methionine Moiety on Initiator tRNA by Translation Factor eIF2

“…8 The gamma subunit of eIF2 is thought to bind both the initiator tRNA and the guanine nucleotide. 21,36,37 The structures of the wild-type protein in the absence of guanine nucleotide and the presence of GDP were determined, as were structures of a mutant form of the protein, G235D (thought to be in or near the MettRNA i binding site), in the absence of ligand and the presence of both GDP and GDPNP. The archaeal gamma subunit bears striking sequence and structural similarities to elongation factor EFTu/eEF1A.…”

The structure and function of initiation factors in eukaryotic protein synthesis

“…The GTPand tRNA i Met -binding sites are in close proximity in EF-Tu [65]. Consensus motif G4 forms part of the guanine ring-binding loop in G proteins; mutations in this motif abrogated or strongly impaired the function of yeast eIF2k in vivo and impaired binding of guanine nucleotides in vitro [57,59]. Binding of initiator tRNA Figure 2.…”