The Saccharomyces cerevisiae Homologue of Mammalian Translation Initiation Factor 6 Does Not Function as a Translation Initiation Factor†
AUTOR(ES)
Si, Kausik
FONTE
American Society for Microbiology
RESUMO
Eukaryotic translation initiation factor 6 (eIF6) binds to the 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit. The Saccharomyces cerevisiae gene that encodes the 245-amino-acid eIF6 (calculated Mr 25,550), designated TIF6, has been cloned and expressed in Escherichia coli. The purified recombinant protein prevents association between 40S and 60S ribosomal subunits to form 80S ribosomes. TIF6 is a single-copy gene that maps on chromosome XVI and is essential for cell growth. eIF6 expressed in yeast cells associates with free 60S ribosomal subunits but not with 80S monosomes or polysomal ribosomes, indicating that it is not a ribosomal protein. Depletion of eIF6 from yeast cells resulted in a decrease in the rate of protein synthesis, accumulation of half-mer polyribosomes, reduced levels of 60S ribosomal subunits resulting in the stoichiometric imbalance in the 40S/60S subunit ratio, and ultimately cessation of cell growth. Furthermore, lysates of yeast cells depleted of eIF6 remained active in translation of mRNAs in vitro. These results indicate that eIF6 does not act as a true translation initiation factor. Rather, the protein may be involved in the biogenesis and/or stability of 60S ribosomal subunits.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=116070Documentos Relacionados
- A Saccharomyces cerevisiae homologue of mammalian translation initiation factor 4B contributes to RNA helicase activity.
- The Saccharomyces cerevisiae translation initiation factor Tif3 and its mammalian homologue, eIF-4B, have RNA annealing activity.
- Phosphorylation of Mammalian Eukaryotic Translation Initiation Factor 6 and Its Saccharomyces cerevisiae Homologue Tif6p: Evidence that Phosphorylation of Tif6p Regulates Its Nucleocytoplasmic Distribution and Is Required for Yeast Cell Growth†
- The Saccharomyces cerevisiae TIF6 Gene Encoding Translation Initiation Factor 6 Is Required for 60S Ribosomal Subunit Biogenesis
- Translation in Saccharomyces cerevisiae: initiation factor 4A-dependent cell-free system.