The Saccharomyces cerevisiae HCR1 gene encoding a homologue of the p35 subunit of human translation initiation factor 3 (eIF3) is a high copy suppressor of a temperature-sensitive mutation in the Rpg1p subunit of yeast eIF3.
The complex eukaryotic initiation factor 3 (eIF3) was shown to promote the formation of the 43 S preinitiation complex by dissociating 40 S and 60 S ribosomal subunits, stabilizing the ternary complex, and aiding mRNA binding to 40 S ribosomal subunits. Recently, we described the identification of RPG1 (TIF32), the p110 subunit of the eIF3 core complex in yeast. In a screen for Saccharomyces cerevisiae multicopy suppressors of the rpg1-1 temperature-sensitive mutant, an unknown gene corresponding to the open reading frame YLR192C was identified. When overexpressed, the 30-kDa gene product, named Hcr1p, was able to support, under restrictive conditions, growth of the rpg1-1 temperature-sensitive mutant, but not of a Rpg1p-depleted mutant. An hcr1 null mutant was viable, but showed slight reduction of growth when compared with the wild-type strain. Physical interaction between the Hcr1 and Rpg1 proteins was shown by co-immunoprecipitation analysis. The combination of Deltahcr1 and rpg1-1 mutations resulted in a synthetic enhancement of the slow growth phenotype at a semipermissive temperature. In a computer search, a significant homology to the human p35 subunit of the eIF3 complex was found. We assume that the yeast Hcr1 protein participates in translation initiation likely as a protein associated with the eIF3 complex.
Valásek
L
L
Vienna Biocenter, Institute of Biochemistry and Molecular Cell Biology, University of Vienna, A-1030 Vienna, Austria. lvalasek@aghmac1.nichd.nih.gov
Hasek
J
J
Trachsel
H
H
Imre
E M
EM
Ruis
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H
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D039621:Eukaryotic Initiation Factor-3; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics*; D010641:Phenotype; D039665:Prokaryotic Initiation Factor-3; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature
D018797:Cell Cycle Proteins; D039621:Eukaryotic Initiation Factor-3; D005656:Fungal Proteins; C121939:HCR1 protein, S cerevisiae; D046911:Macromolecular Substances; D010448:Peptide Initiation Factors; D039665:Prokaryotic Initiation Factor-3; D012333:RNA, Messenger; C111889:RPG1 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins