Yeast Hct1 is a regulator of Clb2 cyclin proteolysis

Cell. 1997 Aug 22;90(4):683-93. doi: 10.1016/s0092-8674(00)80529-2.


Stage-specific proteolysis of mitotic cyclins is fundamental to eukaryotic cell cycle regulation. We found that yeast Hct1, a conserved protein of eukaryotes, is a necessary and rate-limiting component of this proteolysis pathway. In hct1 mutants, the mitotic cyclin Clb2 is highly stabilized and inappropriately induces DNA replication, while G1 cyclins and other proteolytic substrates remain short-lived. Viability of hct1 mutants depends on SIC1. This and further results suggest that inhibition of cyclin-dependent kinases may compensate for defects in cyclin proteolysis. Remarkably, elevated levels of Hct1 ectopically activate destruction box- and Cdc23-dependent degradation of Clb2 and cause phenotypic effects characteristic for a depletion of M-phase cyclins. Hct1 and the related Cdc20 may function as substrate-specific regulators of proteolysis during mitosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anaphase-Promoting Complex-Cyclosome
  • Apc8 Subunit, Anaphase-Promoting Complex-Cyclosome
  • Cdc20 Proteins
  • Cdh1 Proteins
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cyclin B*
  • Cyclin-Dependent Kinases / antagonists & inhibitors
  • Cyclins / metabolism*
  • Down-Regulation
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Fungal Proteins / physiology*
  • Gene Dosage
  • Mitosis
  • Molecular Sequence Data
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins*
  • Ubiquitin-Protein Ligase Complexes


  • Apc8 Subunit, Anaphase-Promoting Complex-Cyclosome
  • CDC20 protein, S cerevisiae
  • CDC23 protein, S cerevisiae
  • CDH1 protein, S cerevisiae
  • CLB2 protein, S cerevisiae
  • Cdc20 Proteins
  • Cdh1 Proteins
  • Cell Cycle Proteins
  • Cyclin B
  • Cyclins
  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Ubiquitin-Protein Ligase Complexes
  • Anaphase-Promoting Complex-Cyclosome
  • Cyclin-Dependent Kinases

Associated data

  • GENBANK/U05340
  • GENBANK/Z72525