Abstract
The γ subunit of eukaryotic translation initiation factor 2 is an EF-Tu-like protein that plays an essential role in protein synthesis. We have isolated an eIF-2γ homolog from the fission yeast Schizosaccharomyces pombe that complements a gcd11 null allele in Saccharomyces cerevisiae. GCD11 is an essential gene that encodes S. cerevisiae eIF-2γ. Comparison among three eIF-2γ homologs from humans, S.␣cerevisiae, and S. pombe, and a putative Drosophila homolog, reveals the presence of a domain N-terminal to the GTP-binding (G) domain that varies in length (relative to EF-Tu) from 12 residues in S. pombe to 89 residues in S. cerevisiae. In S. cerevisiae, these sequences are not essential for function. However, unlike a deletion, a missense mutation in this domain confers a slow growth phenotype and constitutively derepresses expression of the GCN4 transcriptional activator. The eIF-2γ homologs also contain a partially conserved 35–37 amino acid insertion in the G domain that is absent from EF-Tu and other G proteins. Unlike the variable N-terminal domain, these residues are required for the essential function of eIF-2γ.
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Received: 2 September 1996 / Accepted: 25 September 1996
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Erickson, F., Harding, L., Dorris, D. et al. Functional analysis of homologs of translation initiation factor 2γ in yeast. Mol Gen Genet 253, 711–719 (1997). https://doi.org/10.1007/s004380050375
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DOI: https://doi.org/10.1007/s004380050375