Previous Article | Next Article ![]()
Mol. Cell. Biol., Jan 1996, 86-93, Vol 16, No. 1
R Kovelman and P Russell
The DNA replication checkpoint couples the onset of mitosis with the
completion of S phase. It is clear that in the fission yeast
Schizosaccharomyces pombe, operation of this checkpoint requires
maintenance of the inhibitory tyrosyl phosphorylation of Cdc2. Cdc25
phosphatase induces mitosis by dephosphorylating tyrosine 15 of Cdc2. In
this report, Cdc25 is shown to accumulate to a very high level in cells
arrested in S. This shows that mechanisms which modulate the abundance of
Cdc25 are unconnected to the DNA replication checkpoint. Using a
Cdc2/cyclin B activation assay, we found that Cdc25 activity increased
approximately 10-fold during transit through M phase. Cdc25 was activated
by phosphorylations that were dependent on Cdc2 activity in vivo. Cdc25
activation was suppressed in cells arrested in G1 and S. However, Cdc25 was
more highly modified and appeared to be somewhat more active in S than in
G1. This finding might be connected to the fact that progression from G1 to
S increases the likelihood that constitutive Cdc25 overproduction will
cause inappropriate mitosis.
Copyright © 1996, American Society for Microbiology
Stockpiling of Cdc25 during a DNA replication checkpoint arrest in Schizosaccharomyces pombe
Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037, USA.
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»