SKI7/YOR076C Summary Help

Standard Name SKI7 1
Systematic Name YOR076C
Feature Type ORF, Verified
Description Coupling protein for the Ski complex and cytoplasmic exosome; involved in 3'-5' RNA degradation; eRF3-like domain targets nonstop mRNA for degradation; null mutants have superkiller phenotype; SKI7 has a paralog, HBS1, that arose from the whole genome duplication (2, 3, 4, 5, 6, 7 and see Summary Paragraph)
Name Description SuperKIller 1
Chromosomal Location
ChrXV:471620 to 469377 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All SKI7 GO evidence and references
  View Computational GO annotations for SKI7
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 6 genes
Classical genetics
Large-scale survey
191 total interaction(s) for 104 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 62
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 7
  • PCA: 1
  • Reconstituted Complex: 8
  • Two-hybrid: 4

Genetic Interactions
  • Dosage Lethality: 1
  • Negative Genetic: 67
  • Phenotypic Enhancement: 3
  • Positive Genetic: 20
  • Synthetic Growth Defect: 8
  • Synthetic Lethality: 4
  • Synthetic Rescue: 4

Expression Summary
Length (a.a.) 747
Molecular Weight (Da) 84,778
Isoelectric Point (pI) 7.77
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXV:471620 to 469377 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..2244 471620..469377 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Retired NameYOR29-27
Primary SGDIDS000005602

The SKI complex is a cytoplasmic complex composed of a putative RNA helicase (Ski2p), a tetratricopeptide repeat protein (Ski3p) and a WD repeat protein (Ski8p) (8 and references therein). Along with the adaptor protein Ski7p, the SKI complex mediates the cytoplasmic functions of the exosome, a 3'-5' exonuclease complex (3, 4). Together, the SKI complex, Ski7p and the exosome function in a wide range of 3'-5' RNA catabolic processes that include the routine turnover of normal mRNAs (9), the degradation of aberrant mRNAs by 3'-5' nonsense-mediated decay (10) and non-stop mRNA decay (5), and the degradation of other cytoplasmic RNAs including unadenylated RNAs (11) and viral dsRNA (12, 1). Although the SKI complex was originally described as a heterotrimer containing Ski2p, Ski3p and Ski8p (8, 6), later work provides evidence that it is a heterotetramer containing one subunit each of Ski2p and Ski3p, and two subunits of Ski8p (13).

All members of the SKI complex are found in humans and the human genes for hSKI2 (SKIV2L) and hSKI8 (WDR61) have been identified (14, 15, 16). However, Ski7p is found only in a subset of Saccharomyces species (17); the closely related protein, Hbs1p, is likely to fill the role of Ski7p in other fungi and possibly other eukaryotes (18).

Null mutants of ski2, ski3, ski8 and ski7 have similar phenotypes. All have the superkiller phenotype indicative of increased accumulation or viral dsRNA (19 and references therein), and exhibit synthetic lethality with mutations in genes involved in 5'-3' mRNA decay (9, 3).

Although null mutations in SKI7 virtually phenocopy those of SKI2, SKI3 and SKI8, Ski7p is not a member of the SKI complex (8, 4). Instead, Ski7p is thought to function as a coupling factor between the SKI complex and the exosome. The Ski7p protein contains two domains, an N-terminal domain, and a C-terminal "eRF3-like domain" similar to translation termination factor eRF3 (Sup35p). The N-terminal domain is necessary and sufficient for interaction between the SKI complex and the exosome, and for 3'-5' mRNA degradation (4). The C-terminal eRF3-like domain is dispensable for some Ski7p functions, but is thought to be important in non-stop decay, the process by which mRNAs lacking a termination codon are recognized and degraded. The current model for this process suggests that the Ski7p eRF3-like domain binds to an empty aminoacyl-(RNA-binding) site on the stalled ribosome, and this interaction targets the non-stop mRNA for degradation by concerted action of the SKI complex and the exosome (5).

Last updated: 2009-03-24 Contact SGD

References cited on this page View Complete Literature Guide for SKI7
1) Ridley SP, et al.  (1984) Superkiller mutations in Saccharomyces cerevisiae suppress exclusion of M2 double-stranded RNA by L-A-HN and confer cold sensitivity in the presence of M and L-A-HN. Mol Cell Biol 4(4):761-70
2) Benard L, et al.  (1999) The ski7 antiviral protein is an EF1-alpha homolog that blocks expression of non-Poly(A) mRNA in Saccharomyces cerevisiae. J Virol 73(4):2893-900
3) van Hoof A, et al.  (2000) Function of the ski4p (Csl4p) and Ski7p proteins in 3'-to-5' degradation of mRNA. Mol Cell Biol 20(21):8230-43
4) Araki Y, et al.  (2001) Ski7p G protein interacts with the exosome and the Ski complex for 3'-to-5' mRNA decay in yeast. EMBO J 20(17):4684-93
5) van Hoof A, et al.  (2002) Exosome-mediated recognition and degradation of mRNAs lacking a termination codon. Science 295(5563):2262-4
6) Wang L, et al.  (2005) Domain interactions within the Ski2/3/8 complex and between the Ski complex and Ski7p. RNA 11(8):1291-302
7) Byrne KP and Wolfe KH  (2005) The Yeast Gene Order Browser: combining curated homology and syntenic context reveals gene fate in polyploid species. Genome Res 15(10):1456-61
8) Brown JT, et al.  (2000) The yeast antiviral proteins Ski2p, Ski3p, and Ski8p exist as a complex in vivo. RNA 6(3):449-57
9) Jacobs JS, et al.  (1998) The 3' to 5' degradation of yeast mRNAs is a general mechanism for mRNA turnover that requires the SKI2 DEVH box protein and 3' to 5' exonucleases of the exosome complex. EMBO J 17(5):1497-506
10) Mitchell P and Tollervey D  (2003) An NMD pathway in yeast involving accelerated deadenylation and exosome-mediated 3'-->5' degradation. Mol Cell 11(5):1405-13
11) Brown JT and Johnson AW  (2001) A cis-acting element known to block 3' mRNA degradation enhances expression of polyA-minus mRNA in wild-type yeast cells and phenocopies a ski mutant. RNA 7(11):1566-77
12) Toh-E A, et al.  (1978) Chromosomal superkiller mutants of Saccharomyces cerevisiae. J Bacteriol 136(3):1002-7
13) Synowsky SA and Heck AJ  (2008) The yeast Ski complex is a hetero-tetramer. Protein Sci 17(1):119-25
14) Lee SG, et al.  (1995) Identification and characterization of a human cDNA homologous to yeast SKI2. Genomics 25(3):660-6
15) Dangel AW, et al.  (1995) Human helicase gene SKI2W in the HLA class III region exhibits striking structural similarities to the yeast antiviral gene SKI2 and to the human gene KIAA0052: emergence of a new gene family. Nucleic Acids Res 23(12):2120-6
16) Zhu B, et al.  (2005) The human PAF complex coordinates transcription with events downstream of RNA synthesis. Genes Dev 19(14):1668-73
17) Atkinson GC, et al.  (2008) Evolution of nonstop, no-go and nonsense-mediated mRNA decay and their termination factor-derived components. BMC Evol Biol 8:290
18) van Hoof A  (2005) Conserved functions of yeast genes support the duplication, degeneration and complementation model for gene duplication. Genetics 171(4):1455-61
19) Wickner RB  (1996) Double-stranded RNA viruses of Saccharomyces cerevisiae. Microbiol Rev 60(1):250-65