106
proteasomal destruction. Most likely, further studies will identify additional cell
cycle regulators that are regulated in a similar manner.
Acknowledgements We apologise to all colleagues whose work could not be cited because of
space limitations. We thank the members of the Mayer lab for helpful comments on the chapter.
This work was supported by funding from the Konstanz Research School Chemical Biology
(KoRS-CB) and the Collaborative Research Center 969 ‘Chemical and Biological Principles of
Cellular Proteostasis’ of the German Research Foundation (DFG).
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Phosphatases
B55/B‘56/PP1/Fcp1 Emi1
loop
XErp1
synchronousfast asynchronousslow
M
S
M
S
G2 G1
Early embryo Somatic
Spindle assembly
checkpoint
DNA damage
checkpoint
Kinases
Cdk1/Plk1/AurK/CK1
APC/C Gwl/Arpp19
maternal
transcription
zygotic
transcription
Autoamplification
Fig. 3.7 Venn diagram of common and unique regulatory elements of Xenopus early embryonic
and somatic cell cycles
A. Heim et al.