title: GCD11, a negative regulator of GCN4 expression, encodes the gamma subunit of eIF-2 in Saccharomyces cerevisiae.
abstract: The eukaryotic translation initiation factor eIF-2 plays a critical role in regulating the expression of the yeast transcriptional activator GCN4. Mutations in genes encoding the alpha and beta subunits of eIF-2 alter translational efficiency at the GCN4 AUG codon and constitutively elevate GCN4 translation. Mutations in the yeast GCD11 gene have been shown to confer a similar phenotype. The nucleotide sequence of the cloned GCD11 gene predicts a 527-amino-acid polypeptide that is similar to the prokaryotic translation elongation factor EF-Tu. Relative to EF-Tu, the deduced GCD11 amino acid sequence contains a 90-amino-acid N-terminal extension and an internal cysteine-rich sequence that contains a potential metal-binding finger motif. We have identified the GCD11 gene product as the gamma subunit of eIF-2 by the following criteria: (i) sequence identities with mammalian eIF-2 gamma peptides; (ii) increased eIF-2 activity in extracts prepared from cells cooverexpressing GCD11, eIF-2 alpha, and eIF-2 beta; and (iii) cross-reactivity of antibodies directed against the GCD11 protein with the 58-kDa polypeptide present in purified yeast eIF-2. The predicted GCD11 polypeptide contains all of the consensus elements known to be required for guanine nucleotide binding, suggesting that, in Saccharomyces cerevisiae, the gamma subunit of eIF-2 is responsible for GDP-GTP binding.
authors.affiliation: Molecular and Cell Biology Program, University of Texas, Dallas 830688.
authors.forename: E M
authors.initials: EM
authors.lastname: Hannig
authors.forename: A M
authors.initials: AM
authors.lastname: Cigan
authors.forename: B A
authors.initials: BA
authors.lastname: Freeman
authors.forename: T G
authors.initials: TG
authors.lastname: Kinzy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003429:Cross Reactions; D004271:DNA, Fungal / Q000235:genetics; D004268:DNA-Binding Proteins; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D005656:Fungal Proteins / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010444:Peptide Elongation Factor Tu / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics*; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D013552:Swine; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D015852:Eukaryotic Initiation Factor-2; D005656:Fungal Proteins; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D011494:Protein Kinases; D019204:GTP-Binding Proteins; D010444:Peptide Elongation Factor Tu