Vertebrate Development Maternal to Zygotic Control (Advances in Experimental Medicine and Biology)

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CDK1

P

P P

CDK1

CycB

CDK1

CycB

Degradation

Translation Phosphorylation

Dephosphorylation

Pi H 2 O

Cdc25

P

ATP

Cdk1

Wee1/Myt1

ADP

P

APC/C Ub

AAAAAAAAAAA

CycB

CycB

Cdk1

Cdk1 Cdk1

E2

CycB

Ub

Ub

CycB

26S

Fig. 3.3 Cdk1 is the master regulator of cell cycle progression. The activity of Cdk1/cyclin-B is
regulated at the levels of translation and degradation, phosphorylation and dephosphorylation (active
and inactive factors are shown in green and red, respectively. This also applies to Figs. 3.4–6)

CDK1

CycB

P

CDK1

CycB

P P

CDK1

CycB

P

CAK

P

Cdc25P

P

P

P

Wee1/

Myt1

Wee1/

Myt1

P P

Cdc25

P

Plx1

P

P

P

PPPPPPCdc25Cdc25Cdc25Cdc25Cdc25Cdc25Cdc25PP

SCFβ-TRCP

Fig. 3.4 The Cdk1/cyclin-B amplification loop. Cdk1/cyclin-B negatively regulates the activities
of Wee1/Myt1 that act inhibitory on Cdk1 by phosphorylating it at T14/Y15. These inhibitory
phosphorylations are removed by Cdc25, which is under the positive control of Cdk1/cyclin-
B. Cdk1-activating kinase (CAK) constitutively activates Cdk1 by phosphorylating it at the T-loop

A. Heim et al.

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