Two F-box/WD-repeat proteins Pop1 and Pop2 form hetero- and homo-complexes together with cullin-1 in the fission yeast SCF (Skp1-Cullin-1-F-box) ubiquitin ligase

Genes Cells. 1998 Nov;3(11):721-35. doi: 10.1046/j.1365-2443.1998.00225.x.


Background: In the ubiquitin-dependent proteolysis pathway, a ubiquitin ligase (E3) is responsible for substrate selectivity and timing of degradation. A novel E3, SCF (Skp1-Cullin-1/Cdc53-F-box) plays a pivotal role in cell cycle progression. In fission yeast, F-box/WD-repeat protein Pop1 regulates the level of the CDK (cyclin-dependent kinase) inhibitor Rum1 and the S phase regulator Cdc18.

Results: We have cloned and characterized the pop2+ gene which encodes the Pop1-related F-box/WD-repeat protein. Pop2 plays a role which overlaps with Pop1 in the degradation of Rum1 and Cdc18. However, these two proteins are not functional homologues. Pop1 and Pop2 form hetero-as well as homo-dimers in the cell. We have analysed two fission yeast cullin members and found that cullin-1 functions as a component of SCFPop1,2, whilst cullin-3 is involved in the distinct stress-response pathway.

Conclusions: Fission yeast SCF is composed of Pop1 and Pop2, two structurally related but functionally independent F-box/WD-repeat proteins. By forming three distinct complexes, SCFPop1/Pop1, SCFPop1/Pop2 and SCFPop2/Pop2, SCF has evolved a sophisticated mechanism to control the level of Rum1 and Cdc18. Fission yeast SCF also contains cullin-1 as a universal scaffold and each cullin member plays a distinct biological role.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Cycle Proteins / metabolism*
  • Cullin Proteins*
  • Cyclin-Dependent Kinases / antagonists & inhibitors
  • Enzyme Inhibitors / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Genome, Fungal
  • Molecular Sequence Data
  • Mutation
  • Oxidative Stress
  • Peptide Synthases / chemistry
  • Peptide Synthases / genetics
  • Peptide Synthases / metabolism*
  • Phenotype
  • Ribonucleases*
  • Ribonucleoproteins / metabolism*
  • S Phase
  • SKP Cullin F-Box Protein Ligases
  • Saccharomyces cerevisiae Proteins*
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / metabolism*
  • Schizosaccharomyces pombe Proteins*
  • Sequence Homology, Amino Acid
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • Cell Cycle Proteins
  • Cullin 1
  • Cullin Proteins
  • Enzyme Inhibitors
  • Fungal Proteins
  • Ribonucleoproteins
  • Rum1 protein, S pombe
  • Saccharomyces cerevisiae Proteins
  • Schizosaccharomyces pombe Proteins
  • Transcription Factors
  • cdc18 protein, S pombe
  • pop1 protein, S pombe
  • SKP Cullin F-Box Protein Ligases
  • Cyclin-Dependent Kinases
  • Ribonucleases
  • POP2 protein, S cerevisiae
  • Peptide Synthases

Associated data

  • GENBANK/AB016896