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In the initiation phase of eukaryotic translation, eIF5 stimulates the hydrolysis of GTP bound to eIF2 in the 40S ribosomal pre-initiation complex, and the resultant GDP on eIF2 is replaced with GTP by the complex nucleotide exchange factor, eIF2B. Bipartite motifs rich in aromatic and acidic residues are conserved at the C-termini of eIF5 and the catalytic(More)
Gcd10p and Gcd14p are essential proteins required for the initiation of protein synthesis and translational repression of GCN4 mRNA. The phenotypes of gcd10 mutants were suppressed by high-copy-number IMT genes, encoding initiator methionyl tRNA (tRNAiMet), or LHP1, encoding the yeast homolog of the human La autoantigen. The gcd10-504 mutation led to a(More)
The PRT1, TIF34, GCD10, and SUI1 proteins of Saccharomyces cerevisiae were found previously to copurify with eukaryotic translation initiation factor 3 (eIF3) activity. Although TIF32, NIP1, and TIF35 are homologous to subunits of human eIF3, they were not known to be components of the yeast factor. We detected interactions between PRT1, TIF34, and TIF35 by(More)
Only five of the nine subunits of human eukaryotic translation initiation factor 3 (eIF3) have recognizable homologs encoded in the Saccharomyces cerevisiae genome, and only two of these (Prt1p and Tif34p) were identified previously as subunits of yeast eIF3. We purified a polyhistidine-tagged form of Prt1p (His-Prt1p) by Ni2+ affinity and gel filtration(More)
eIF5 stimulates the GTPase activity of eIF2 bound to Met-tRNA(i)(Met), and its C-terminal domain (eIF5-CTD) bridges interaction between eIF2 and eIF3/eIF1 in a multifactor complex containing Met-tRNA(i)(Met). The tif5-7A mutation in eIF5-CTD, which destabilizes the multifactor complex in vivo, reduced the binding of Met-tRNA(i)(Met) and mRNA to 40S subunits(More)
Yeast translation initiation factor 3 contains five core subunits (known as TIF32, PRT1, NIP1, TIF34 and TIF35) and a less tightly associated component known as HCR1. We found that a stable subcomplex of His8-PRT1, NIP1 and TIF32 (PN2 subcomplex) could be affinity purified from a strain overexpressing these eIF3 subunits. eIF5, eIF1 and HCR1 co-purified(More)
Conversion of a nascent precursor tRNA to a mature functional species is a multipartite process that involves the sequential actions of several processing and modifying enzymes. La is the first protein to interact with pre-tRNAs in eukaryotes. An opal suppressor tRNA served as a functional probe to examine the activities of yeast and human (h)La proteins in(More)
The murine int-6 locus, identified as a frequent integration site of mouse mammary tumor viruses, encodes the 48-kDa eIF3e subunit of translation initiation factor eIF3. Previous studies indicated that the catalytically active core of budding yeast eIF3 consists of five subunits, all conserved in eukaryotes, but does not contain a protein closely related to(More)
The modified nucleoside 1-methyladenosine (m(1)A) is found at position 58 in the TPsiC loop of many eukaryotic tRNAs. The absence of m(1)A from all tRNAs in Saccharomyces cerevisiae mutants lacking Gcd10p elicits severe defects in processing and stability of initiator methionine tRNA (tRNA(i)(Met)). Gcd10p is found in a complex with Gcd14p, which contains(More)
14-3-3σ, a gene upregulated by p53 in response to DNA damage, exists as part of a positive-feedback loop, which activates p53 and is a human cancer epithelial marker downregulated in various cancer types. 14-3-3σ levels are critical for maintaining p53 activity in response to DNA damage and regulating signal mediators such as Akt. In this study, we identify(More)