Schultz et al. (1998) Proc. Natl. Acad. Sci. USA 95, 5857-5864
Letunic et al. (2012) Nucleic Acids Res , doi:10.1093/nar/gkr931

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eIF6 translation initiation factor 6

SMART accession number:	SM00654
Description:
Interpro abstract (IPR002769):	This family includes eukaryotic translation initiation factor 6 (eIF6) as well as presumed archaeal homologues. The assembly of 80S ribosomes requires joining of the 40S and 60S subunits, which is triggered by the formation of an initiation complex on the 40S subunit. This event is rate-limiting for translation, and depends on external stimuli and the status of the cell. Eukaryotic translation initiation factor 6 (eIF6) binds specifically to the free 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit ribosomes [(PUBMED:9891075)]. Furthermore, eIF6 interacts in the cytoplasm with RACK1, a receptor for activated protein kinase C (PKC). RACK1 is a major component of translating ribosomes, which harbour significant amounts of PKC. Loading 60S subunits with eIF6 caused a dose-dependent translational block and impairment of 80S formation, which are reversed by expression of RACK1 and stimulation of PKC in vivo and in vitro. PKC stimulation leads to eIF6 phosphorylation and its release, promoting 80S subunit formation. RACK1 provides a physical and functional link between PKC signalling and ribosome activation.
GO process:	mature ribosome assembly (GO:0042256)
GO function:	ribosome binding (GO:0043022)
Family alignment:	View or CHROMA formatCLUSTALW formatMSF formatFASTA formatPIR format

There are 283 eIF6 domains in 283 proteins in SMART's nrdb database.

Click on the following links for more information.

• Evolution (species in which this domain is found)

• Click on to expand nodes. To display all proteins with a eIF6 domain in a specific node, click on it.

  This tree shows only several representative species. The complete taxonomic breakdown of all proteins with eIF6 domain is also avaliable.

  Useful shortcuts: Expand all nodes or Collapse tree
  Go to specific node: Anopheles gambiae, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens, Mus musculus, Rattus norvegicus, Saccharomyces cerevisiae, Takifugu rubripes

• Cellular role (predicted cellular role)

• Cellular role: translation
  Binding / catalysis: RNA

• Literature (relevant references for this domain)

• Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.

  • Si K, Maitra U
  • The Saccharomyces cerevisiae homologue of mammalian translation initiation factor 6 does not function as a translation initiation factor.
  • Mol Cell Biol. 1999; 19: 1416-26
  • Display abstract

  • 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.

• Structure (3D structures containing this domain)

• 3D Structures of eIF6 domains in PDB

  PDB code	Main view	Title
  1g61		Crystal structure of m.jannaschii eif6
  1g62		Crystal structure of s.cerevisiae eif6

• Links (links to other resources describing this domain)

• PFAM	eIF6
  INTERPRO	IPR002769

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