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Gene Review

SKP1  -  SCF ubiquitin ligase subunit SKP1

Saccharomyces cerevisiae S288c

Synonyms: CBF3D, Centromere DNA-binding protein complex CBF3 subunit D, D9798.14, E3 ubiquitin ligase complex SCF subunit SKP1, Suppressor of kinetochore protein 1, ...
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Disease relevance of SKP1

  • Here we describe the fortuitous cloning of cDNAs for two Skp1 homologues from the plant Arabidopsis thaliana on account of their ability to activate reporter gene expression in yeast directed by the cyt-1 element from the promoter of the Agrobacterium tumefaciens T-cyt gene, which is essential for expression of the gene in plants [1].

High impact information on SKP1


Biological context of SKP1

  • We have previously shown that SKP1 and SGT1 balance the assembly and turnover of CBF3 complexes, a cycle that we suggest is independent of its role in chromosome segregation (Rodrigo-Brenni, M.C., S. Thomas, D.C. Bouck, and K.B. Kaplan. 2004. Mol. Biol. Cell. 15:3366-3378) [6].
  • Thus, in contrast to the current view, phosphorylation of Ctf13p and Skp1p is not essential for the formation of CBF3-centromere DNA complexes [7].
  • A stable truncated Cdc4pF-beta-gal hybrid protein capable of binding Skp1p and entering into an SCF complex interfered with proteolysis of SCF targets and inhibited cell proliferation [8].
  • Here, we show that the silencing suppressor protein P0 of two Arabidopsis-infecting poleroviruses interacts by means of a conserved minimal F-box motif with Arabidopsis thaliana orthologs of S-phase kinase-related protein 1 (SKP1), a component of the SCF family of ubiquitin E3 ligases [9].
  • Point mutations in the F-box-like motif abolished the P0-SKP1 ortholog interaction, diminished virus pathogenicity, and inhibited the silencing suppressor activity of P0 [9].

Anatomical context of SKP1

  • Rav1, Rav2 and Skp1 form a complex that we have named 'regulator of the (H+)-ATPase of the vacuolar and endosomal membranes' (RAVE), which associates with the V1 domain of the vacuolar membrane (H+)-ATPase (V-ATPase) [10].
  • Suppression of Skp1 in mitotic HeLa cells by siRNA resulted in accumulation of telophase cells with elongated inter-cell bridges and with midbodies stretched 2-3 times longer than that of normal cells [11].

Associations of SKP1 with chemical compounds

  • The SKP1 gene of Kluyveromyces lactis was isolated as a suppressor of a lethal temperature-sensitive mutation in the Saccharomyces cerevisiae CTF13 gene (Chromosome Transmission Factor 13) [12].
  • The Grr1-Skp1 interaction is enhanced by high levels of glucose [13].
  • The fragmin60 C2 domain does not bind phospholipids but interacts with the endogenous homologue of Saccharomyces cerevisiae S-phase kinase-associated protein (Skp1), as shown by pull-down assays and co-expression in mammalian cells [14].
  • The association of Met30 with Skp1 but not with its substrate Met4 was inhibited in cells treated with cadmium [15].
  • Furthermore, nuclear concentration occurred in a mutant that attached only the core disaccharide to Skp1 [16].

Physical interactions of SKP1

  • Here, we investigate how the Ctf13p/Skp1p complex becomes competent to form the CBF3-centromere DNA complex [7].
  • Formation of the active Ctf13-Skp1 complex also requires Hsp90, a molecular chaperone [17].
  • Skp1 binds a motif called the F-box and in turn F-box proteins appear to recruit specific substrates for ubiquitination [5].
  • Coimmunoprecipitation assays reveal that Mfb1p interacts with Skp1p in an F-box-dependent manner [18].
  • Importantly, Skp1p was the only major partner that copurified with Rcy1p [19].

Enzymatic interactions of SKP1

  • Cdc4 assembled with Skp1 functions as the receptor that selectively binds phosphorylated Sic1 [20].
  • These data suggest that Grr1 is required for degradation of Cln2 through linking phosphorylated Cln2 to Skp1 in a SCFGrr1 complex [21].

Other interactions of SKP1

  • Sgt1p physically associates with Skp1p in vivo and in vitro [22].
  • As revealed by mass spectrometry, Ctf13p and Skp1p carry two and four phosphate groups, respectively [7].
  • A skp1 mutation together with Hsp90 mutations exhibits synthetic lethality [7].
  • These results strongly suggest that Grr1 functions in the ubiquitin pathway through association with Skp1 [23].
  • In Saccharomyces cerevisiae, an SCF complex contains a common set of components, namely, Cdc53p, Skp1p, and Hrt1p [24].

Analytical, diagnostic and therapeutic context of SKP1


  1. Overexpression of Arabidopsis thaliana SKP1 homologues in yeast inactivates the Mig1 repressor by destabilising the F-box protein Grr1. Schouten, J., de Kam, R.J., Fetter, K., Hoge, J.H. Mol. Gen. Genet. (2000) [Pubmed]
  2. A complex of Cdc4p, Skp1p, and Cdc53p/cullin catalyzes ubiquitination of the phosphorylated CDK inhibitor Sic1p. Feldman, R.M., Correll, C.C., Kaplan, K.B., Deshaies, R.J. Cell (1997) [Pubmed]
  3. Regulating the yeast kinetochore by ubiquitin-dependent degradation and Skp1p-mediated phosphorylation. Kaplan, K.B., Hyman, A.A., Sorger, P.K. Cell (1997) [Pubmed]
  4. Budding yeast SKP1 encodes an evolutionarily conserved kinetochore protein required for cell cycle progression. Connelly, C., Hieter, P. Cell (1996) [Pubmed]
  5. Cdc53 is a scaffold protein for multiple Cdc34/Skp1/F-box proteincomplexes that regulate cell division and methionine biosynthesis in yeast. Patton, E.E., Willems, A.R., Sa, D., Kuras, L., Thomas, D., Craig, K.L., Tyers, M. Genes Dev. (1998) [Pubmed]
  6. A novel role for the CBF3 kinetochore-scaffold complex in regulating septin dynamics and cytokinesis. Gillis, A.N., Thomas, S., Hansen, S.D., Kaplan, K.B. J. Cell Biol. (2005) [Pubmed]
  7. Hsp90 enables Ctf13p/Skp1p to nucleate the budding yeast kinetochore. Stemmann, O., Neidig, A., Köcher, T., Wilm, M., Lechner, J. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
  8. Ubiquitination and degradation of the substrate recognition subunits of SCF ubiquitin-protein ligases. Zhou, P., Howley, P.M. Mol. Cell (1998) [Pubmed]
  9. F-box-like domain in the polerovirus protein P0 is required for silencing suppressor function. Pazhouhandeh, M., Dieterle, M., Marrocco, K., Lechner, E., Berry, B., Brault, V., Hemmer, O., Kretsch, T., Richards, K.E., Genschik, P., Ziegler-Graff, V. Proc. Natl. Acad. Sci. U.S.A. (2006) [Pubmed]
  10. Skp1 forms multiple protein complexes, including RAVE, a regulator of V-ATPase assembly. Seol, J.H., Shevchenko, A., Shevchenko, A., Deshaies, R.J. Nat. Cell Biol. (2001) [Pubmed]
  11. Interaction of Skp1 with CENP-E at the midbody is essential for cytokinesis. Liu, D., Zhang, N., Du, J., Cai, X., Zhu, M., Jin, C., Dou, Z., Feng, C., Yang, Y., Liu, L., Takeyasu, K., Xie, W., Yao, X. Biochem. Biophys. Res. Commun. (2006) [Pubmed]
  12. Isolation and partial characterization of the Kluyveromyces lactis homologue of SKP1. Winkler, A.A., Goedegebure, R.H., Zonneveld, B.J., Steensma, H.Y., Hooykaas, P.J. Curr. Genet. (2000) [Pubmed]
  13. Grr1 of Saccharomyces cerevisiae is connected to the ubiquitin proteolysis machinery through Skp1: coupling glucose sensing to gene expression and the cell cycle. Li, F.N., Johnston, M. EMBO J. (1997) [Pubmed]
  14. Fragmin60 encodes an actin-binding protein with a C2 domain and controls actin Thr-203 phosphorylation in Physarum plasmodia and sclerotia. Sklyarova, T., De Corte, V., Meerschaert, K., Devriendt, L., Vanloo, B., Bailey, J., Cook, L.J., Goethals, M., Van Damme, J., Puype, M., Vandekerckhove, J., Gettemans, J. J. Biol. Chem. (2002) [Pubmed]
  15. The yeast ubiquitin ligase SCFMet30 regulates heavy metal response. Yen, J.L., Su, N.Y., Kaiser, P. Mol. Biol. Cell (2005) [Pubmed]
  16. Analysis of Skp1 glycosylation and nuclear enrichment in Dictyostelium. Sassi, S., Sweetinburgh, M., Erogul, J., Zhang, P., Teng-Umnuay, P., West, C.M. Glycobiology (2001) [Pubmed]
  17. Sgt1 associates with Hsp90: an initial step of assembly of the core kinetochore complex. Bansal, P.K., Abdulle, R., Kitagawa, K. Mol. Cell. Biol. (2004) [Pubmed]
  18. The novel F-box protein Mfb1p regulates mitochondrial connectivity and exhibits asymmetric localization in yeast. Kondo-Okamoto, N., Ohkuni, K., Kitagawa, K., McCaffery, J.M., Shaw, J.M., Okamoto, K. Mol. Biol. Cell (2006) [Pubmed]
  19. Skp1p and the F-box protein Rcy1p form a non-SCF complex involved in recycling of the SNARE Snc1p in yeast. Galan, J.M., Wiederkehr, A., Seol, J.H., Haguenauer-Tsapis, R., Deshaies, R.J., Riezman, H., Peter, M. Mol. Cell. Biol. (2001) [Pubmed]
  20. F-box proteins are receptors that recruit phosphorylated substrates to the SCF ubiquitin-ligase complex. Skowyra, D., Craig, K.L., Tyers, M., Elledge, S.J., Harper, J.W. Cell (1997) [Pubmed]
  21. An essential function of Grr1 for the degradation of Cln2 is to act as a binding core that links Cln2 to Skp1. Kishi, T., Yamao, F. J. Cell. Sci. (1998) [Pubmed]
  22. SGT1 encodes an essential component of the yeast kinetochore assembly pathway and a novel subunit of the SCF ubiquitin ligase complex. Kitagawa, K., Skowyra, D., Elledge, S.J., Harper, J.W., Hieter, P. Mol. Cell (1999) [Pubmed]
  23. Grr1 functions in the ubiquitin pathway in Saccharomyces cerevisiae through association with Skp1. Kishi, T., Seno, T., Yamao, F. Mol. Gen. Genet. (1998) [Pubmed]
  24. The abundance of Met30p limits SCF(Met30p) complex activity and is regulated by methionine availability. Smothers, D.B., Kozubowski, L., Dixon, C., Goebl, M.G., Mathias, N. Mol. Cell. Biol. (2000) [Pubmed]
  25. Skp1 and the F-box protein Pof6 are essential for cell separation in fission yeast. Hermand, D., Bamps, S., Tafforeau, L., Vandenhaute, J., Mäkelä, T.P. J. Biol. Chem. (2003) [Pubmed]
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