A complex of Cdc4p, Skp1p, and Cdc53p/cullin catalyzes ubiquitination of the phosphorylated CDK inhibitor Sic1p

R. M Renny Feldman, Craig C. Correll, Kenneth B. Kaplan, Raymond J. Deshaies

Research output: Contribution to journalArticle

680 Scopus citations

Abstract

In S. cerevisiae, the G1/S transition requires Cdc4p, Cdc34p, Cdc53p, Skp1p, and the Cln/Cdc28p cyclin-dependent kinase (Cdk). These proteins are thought to promote the proteolytic inactivation of the S-phase Cdk inhibitor Sic1p. We show here that Cdc4p, Cdc53p, and Skp1p assemble into a ubiquitin ligase complex named SCF(Cdc4p). When mixed together, SCF(Cdc4p) subunits, E1 enzyme, the E2 enzyme Cdc34p, and ubiquitin are sufficient to reconstitute ubiquitination of Cdk-phosphorylated Sic1p. Phosphorylated Sic1p substrate is specifically targeted for ubiquitination by binding to a Cdc4p/Skp1p subcomplex. Taken together, these data illuminate the molecular basis for the G1/S transition in budding yeast and suggest a general mechanism for phosphorylation-targeted ubiquitination in eukaryotes.

Original languageEnglish (US)
Pages (from-to)221-230
Number of pages10
JournalCell
Volume91
Issue number2
DOIs
StatePublished - Oct 17 1997
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology

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