Yeast Hct1 is a regulator of Clb2 cyclin proteolysis.

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.
Mesh Terms:
Amino Acid Sequence, Cell Cycle Proteins, Cyclin B, Cyclin-Dependent Kinases, Cyclins, Down-Regulation, Fungal Proteins, Gene Dosage, Mitosis, Molecular Sequence Data, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Ubiquitin-Protein Ligase Complexes
Cell
Date: Aug. 22, 1997
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