Previous Article | Next Article ![]()
Mol. Cell. Biol., 03 1997, 1212-1223, Vol 17, No. 3
V Measday, L Moore, R Retnakaran, J Lee, M Donoviel, AM Neiman and B Andrews
In budding yeast, entry into the mitotic cell cycle, or Start, requires the
Cdc28 cyclin-dependent kinase (Cdk) and one of its three associated G1
cyclins, Cln1, Cln2, or Cln3. In addition, two other G1 cyclins, Pcl1 and
Pcl2, associate with a second Cdk, Pho85, to contribute to Start. Although
Pho85 is not essential for viability, Pcl1,2-Pho85 kinase complexes become
essential for Start in the absence of Cln1,2- Cdc28 kinases. In addition,
Pho85 interacts with a third cyclin, Pho80, to regulate acid phosphatase
gene expression. Other cellular roles for Pho85 cyclin-Cdk complexes are
suggested by the multiple phenotypes associated with deletion of PHO85, in
addition to Start defects and deregulated acid phosphatase gene expression.
Strains with pho80, pcl1, and pcl2 deletions show only a subset of the
pho85 mutant phenotypes, suggesting the existence of additional Pho85
cyclins (Pcls). We used two-hybrid screening and database searching to
identify seven additional cyclin-related genes that may interact with
Pho85. We found that all of the new genes encode proteins that interacted
with Pho85 in an affinity chromatography assay. One of these genes, CLG1,
was previously suggested to encode a cyclin, based on the protein's
sequence homology to Pcl1 and Pcl2. We have named the other genes PCL5,
PCL6, PCL7, PCL8, PCL9, and PCL10. On the basis of sequence similarities,
the PCLs can be divided into two subfamilies: the Pcl1,2- like subfamily
and the Pho80-like subfamily. We found that deletion of members of the
Pcl1,2 class of genes resulted in pronounced morphological abnormalities.
In addition, we found that expression of one member of the Pcl1,2
subfamily, PCL9, is cell cycle regulated and is decreased in cells arrested
in G1 by pheromone treatment. Our studies suggest that Pho85 associates
with multiple cyclins and that subsets of cyclins may direct Pho85 to
perform distinct roles in cell growth and division.
Copyright © 1997, American Society for Microbiology
A family of cyclin-like proteins that interact with the Pho85 cyclin- dependent kinase
Department of Molecular and Medical Genetics, University of Toronto, Canada.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»