Specialization and targeting of B-type cyclins

Mol Cell. 1999 Jul;4(1):11-9. doi: 10.1016/s1097-2765(00)80183-5.


The B-type cyclins of S. cerevisiae are diversified with respect to time of expression during the cell cycle as well as biological function. We replaced the early-expressed CLB5 coding sequence with the late-expressed CLB2 coding sequence, at the CLB5 locus. CLB5::CLB2 exhibited almost no rescue of clb5-specific replication defects, although it could rescue clb1 clb2 lethality, and in synchronized cells Clb2p-associated kinase activity from CLB5::CLB2 rose early in the cell cycle, similar to that of Clb5p. Mutagenesis of a potential substrate-targeting domain of CLB5 reduced biological activity without reducing Clb5p-associated kinase activity. Thus, Clb5p may have targeting domains required for CLB5-specific biological activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Cycle / genetics
  • Cyclin B / genetics*
  • DNA Replication / genetics
  • Flow Cytometry
  • Fungal Proteins / genetics*
  • Gene Expression Regulation, Fungal
  • Genes, Lethal
  • Mutagenesis
  • Promoter Regions, Genetic
  • Protein Kinases / genetics
  • Saccharomyces cerevisiae / genetics*


  • Cyclin B
  • Fungal Proteins
  • Protein Kinases