The amino acid sequence of eukaryotic translation initiation factor 1 and its similarity to yeast initiation factor SUI1

Kasperaitis, Marcelle A.M.; Voorma, Harry O.; Thomas, Adri A. M.

doi:10.1016/0014-5793(95)00427-b

Cited by 26 publications

(24 citation statements)

References 22 publications

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“…pl6/SUI1 has been identified as an initiation factor previously listed as eIFl [32]. The best characterized polypeptide of eIF3 is yeast PRTI [29,301.…”

Section: Mechanism Of Initiationmentioning

confidence: 99%

“…B., personal communication) has led to the identification of the yeast polypeptides p90, p62, p39 and p16 as PRTI, GCD10, p36 and SUIl, respectively; the yeast p39 subunit is homologous to the p36 subunit of human eIF3. pl6/SUI1 has been identified as an initiation factor previously listed as eIFl [32]. The best characterized polypeptide of eIF3 is yeast PRTI [29, 301. The N-terminal domain contains an RNA recognition motif and is probably involved in ribosome binding [33].…”

Section: Formation Of the 43s Preinitiation Complexmentioning

confidence: 99%

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Initiation of Protein Synthesis in Eukaryotic Cells

Pain

1996

European Journal of Biochemistry

676

471

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It is becoming increasingly apparent that translational control plays an important role in the regulation of gene expression in eukaryotic cells. Most of the known physiological effects on translation are exerted at the level of polypeptide chain initiation. Research on initiation of translation over the past five years has yielded much new information, which can be divided into three main areas: (a) structure and function of initiation factors (including identification by sequencing studies of consensus domains and motifs) and investigation of protein-protein and protein-RNA interactions during initiation ; (b) physiological regulation of initiation factor activities and (c) identification of features in the 5' and 3' untranslated regions of messenger RNA molecules that regulate the selection of these mRNAs for translation. This review aims to assess recent progress in these three areas and to explore their interrelationships.Keywords: translation; initiation; mRNA ; review, regulation.In 1986 I published a review describing the mechanism and regulation of initiation of translation in mammalian cells 121. By that time most of the polypeptide initiation factors catalysing this process had been extensively purified and their individual activities studied in various in vitro systems. Several of them had been shown to be phosphoproteins and, in one case, eukaryotic initiation factor-2 (eIF-2), the effects of phosphorylation had been elucidated and two physiological kinases had been identified. There seemed to be a feeling in some circles that the most interesting problems in protein synthesis had been solved, and that only a few rather boring nuts and bolts awaited discovery.Over the intervening ten years there has been an explosion of research activity in this area, largely fuelled by information yielded by molecular biology and genetic techniques. Cloning of cDNAs encoding initiation factors has revealed domain structures indicative of function and potential regulatory mechanisms. Experiments exploiting the ability to elucidate and manipulate mRNA sequences have demonstrated that translational control contributes to changes in patterns of gene expression during growth, differentiation and development to an extent that would have seemed inconceivable in 1985. Such experiments have, in particular, revealed important roles for structural fea- UTR, untranslated region (in mRNA); RRM, RNA recognition motif; ORF, open reading frame; EMCV, encephalomyocarditis virus ; FMDV, foot-and-mouth disease virus ; IRES, internal ribosome entry segment ; PTB, polypyrimidine tract binding protein ; HCR, heme-controlled repressor; PKR, protein kinase activated by RNA; dsRNA, doublestranded RNA; p70ShK and p 9 0 k , 70 kDa and 90-92 kDa ribosomal protein S6 kinases ; GSK, glycogen synthase kinase ; IRE, iron-regulatory element; IRP, iron regulatory protein ; PABP, poly(A) binding protein; AMV, alfalfa mosaic virus ; CPE, cytoplasmic polyadenylation element (also known as ACE, adenylation control element); MAP, mitogenactivated protei...

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“…pl6/SUI1 has been identified as an initiation factor previously listed as eIFl [32]. The best characterized polypeptide of eIF3 is yeast PRTI [29,301.…”

Section: Mechanism Of Initiationmentioning

confidence: 99%

Section: Formation Of the 43s Preinitiation Complexmentioning

confidence: 99%

Initiation of Protein Synthesis in Eukaryotic Cells

Pain

1996

European Journal of Biochemistry

676

471

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“…Through this reversion analysis, three suppressor genes were found that can initiate translation via a mismatched codon/anticodon between a UUG codon and the initiator-tRNA. The sui1 gene copurifies in part with the yeast translation initiation factor, eIF-3 (Naranda et al 1996), and a mammalian homolog of Sui1 has been reported to correspond to the translation initiation factor eIF-1 (Kasperaitis et al 1995). At present the function of Sui1 is unknown.…”

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confidence: 99%

GTP hydrolysis controls stringent selection of the AUG start codon during translation initiation inSaccharomyces cerevisiae

Huang¹,

Yoon²,

Hannig³

et al. 1997

Genes Dev.

211

275

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We have isolated and characterized two suppressor genes, SUI4 and SUI5, that can initiate translation in the absence of an AUG start codon at the HIS4 locus in Saccharomyces cerevisiae. Both suppressor genes are dominant in diploid cells and lethal in haploid cells. The SUI4 suppressor gene is identical to the GCD11 gene, which encodes the ␥ subunit of the eIF-2 complex and contains a mutation in the G 2 motif, one of the four signature motifs that characterizes this subunit to be a G-protein. The SUI5 suppressor gene is identical to the TIF5 gene that encodes eIF-5, a translation initiation factor known to stimulate the hydrolysis of GTP bound to eIF-2 as part of the 43S preinitiation complex. Purified mutant eIF-5 is more active in stimulating GTP hydrolysis in vitro than wild-type eIF-5, suggesting that an alteration of the hydrolysis rate of GTP bound to the 43S preinitiation complex during ribosomal scanning allows translation initiation at a non-AUG codon. Purified mutant eIF-2␥ complex is defective in ternary complex formation and this defect correlates with a higher rate of dissociation from charged initiator-tRNA in the absence of GTP hydrolysis. Biochemical characterization of SUI3 suppressor alleles that encode mutant forms of the ␤ subunit of eIF-2 revealed that these mutant eIF-2 complexes have a higher intrinsic rate of GTP hydrolysis, which is eIF-5 independent. All of these biochemical defects result in initiation at a UUG codon at the his4 gene in yeast. These studies in light of other analyses indicate that GTP hydrolysis that leads to dissociation of eIF-2 ⅐ GDP from the initiator-tRNA in the 43S preinitiation complex serves as a checkpoint for a 3-bp codon/anticodon interaction between the AUG start codon and the initiator-tRNA during the ribosomal scanning process.

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“…Sui1p is an essential protein identified genetically by its role in ribosomal recognition of the AUG start codon during scanning (7) and is 57% identical in amino acid sequence to rabbit eIF1 (14). Gcd10p is an essential RNA-binding protein first identified by its involvement in regulating translation initiation on GCN4 mRNA.…”

mentioning

confidence: 99%

Nip1p Associates with 40 S Ribosomes and the Prt1p Subunit of Eukaryotic Initiation Factor 3 and Is Required for Efficient Translation Initiation

Greenberg¹,

Phan²,

Gu³

et al. 1998

Journal of Biological Chemistry

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Nip1p is an essential Saccharomyces cerevisiae protein that was identified in a screen for temperature conditional (ts) mutants exhibiting defects in nuclear transport. New results indicate that Nip1p has a primary role in translation initiation. Polysome profiles indicate that cells depleted of Nip1p and nip1-1 cells are defective in translation initiation, a conclusion that is supported by a reduced rate of protein synthesis in Nip1p-depleted cells. Nip1p cosediments with free 40 S ribosomal subunits and polysomal preinitiation complexes, but not with free or elongating 80 S ribosomes or 60 S subunits. Nip1p can be isolated in an about 670-kDa complex containing polyhistidine-tagged Prt1p, a subunit of translation initiation factor 3, by binding to Ni 2؉ -NTA-agarose beads in a manner completely dependent on the tagged form of Prt1p. The nip1-1 ts growth defect was suppressed by the deletion of the ribosomal protein, RPL46. Also, nip1-1 mutant cells are hypersensitive to paromomycin. These results suggest that Nip1p is a subunit of eukaryotic initiation factor 3 required for efficient translation initiation.Translation initiation can be considered to begin with the dissociation of 80 S ribosomes into free 40 S and 60 S subunits which then reassociate with mRNAs in a highly regulated and complex process. Initiation of cap-dependent translation in eukaryotes begins with the binding of a 43 S preinitiation complex to the 5Ј cap of the mRNA. The 43 S ribosome migrates down the mRNA to the translation start site where it is joined by a 60 S ribosomal subunit to complete the assembly of an apparatus capable of accurately forming the first peptide bond. Translation initiation is mediated by at least 10 translation initiation factors, many of which contain multiple subunits that are conserved between yeast and mammals (reviewed in Refs. 1). eIF3 1 is the most complex initiation factor and the one which is least understood with regard to both composition and function. Human eIF3, which is composed of at least nine distinct subunits (2-5), stimulates multiple steps of translation initiation, including the dissociation of 80 S ribosomes, stabilizing tRNA i Met binding to 40 S ribosomal subunits, and binding of mRNA to 40 S subunits (1). A yeast eIF3 complex was purified on the basis of replacing mammalian eIF3 in an in vitro translation initiation assay (6). This complex contains eight subunits of masses 16,21,29,33,39,62, 90, and 135 kDa. The 16-, 39-, 62-, and 90-kDa subunits were identified as Sui1p (7, 8), Tif34p (9) Gcd10p (10), and Prt1p (11), respectively. Yeast Prt1p is 36% identical to the 116-kDa subunit of human eIF3, and Tif34p, a WD repeat protein, is 46% identical to the p36 subunit of human eIF3. Tif34p is required for cell cycle progression and mating as well as translation initiation (12). However, Gcd10p and Sui1p do not show strong similarities to any human eIF3 subunits (13). p33 was shown to interact with Tif34p and Prt1p by two-hybrid analysis and co-immunoprecipitation. It has a RNA-binding domain ...

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The amino acid sequence of eukaryotic translation initiation factor 1 and its similarity to yeast initiation factor SUI1

Cited by 26 publications

References 22 publications

Initiation of Protein Synthesis in Eukaryotic Cells

Initiation of Protein Synthesis in Eukaryotic Cells

GTP hydrolysis controls stringent selection of the AUG start codon during translation initiation inSaccharomyces cerevisiae

Nip1p Associates with 40 S Ribosomes and the Prt1p Subunit of Eukaryotic Initiation Factor 3 and Is Required for Efficient Translation Initiation

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