Recruitment of Cdc28 by Whi3 restricts nuclear accumulation of the G1 cyclin-Cdk complex to late G1

EMBO J. 2004 Jan 14;23(1):180-90. doi: 10.1038/sj.emboj.7600022. Epub 2003 Dec 18.


The G1 cyclin Cln3 is a key activator of cell-cycle entry in budding yeast. Here we show that Whi3, a negative G1 regulator of Cln3, interacts in vivo with the cyclin-dependent kinase Cdc28 and regulates its localization in the cell. Efficient interaction with Cdc28 depends on an N-terminal domain of Whi3 that is also required for cytoplasmic localization of Cdc28, and for proper regulation of G1 length and filamentous growth. On the other hand, nuclear accumulation of Cdc28 requires the nuclear localization signal of Cln3, which is also found in Whi3 complexes. Both Cln3 and Cdc28 are mainly cytoplasmic during early G1, and become nuclear in late G1. However, Whi3-deficient cells show a distinct nuclear accumulation of Cln3 and Cdc28 already in early G1. We propose that Whi3 constitutes a cytoplasmic retention device for Cln3-Cdc28 complexes, thus defining a key G1 event in yeast cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • CDC28 Protein Kinase, S cerevisiae / metabolism*
  • Cell Nucleus / metabolism*
  • Cyclin G
  • Cyclin-Dependent Kinases / metabolism*
  • Cyclins / genetics
  • Cyclins / metabolism*
  • Cytoplasm / chemistry
  • Fluorescent Antibody Technique, Indirect
  • Microscopy, Confocal
  • Models, Molecular
  • Mutation
  • Precipitin Tests
  • Protein Structure, Tertiary
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / chemistry
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Time Factors


  • CLN3 protein, S cerevisiae
  • Cyclin G
  • Cyclins
  • RNA, Messenger
  • RNA-Binding Proteins
  • Saccharomyces cerevisiae Proteins
  • Whi3 protein, S cerevisiae
  • CDC28 Protein Kinase, S cerevisiae
  • Cyclin-Dependent Kinases