Two major classes of actin-nucleating proteins:

1. Formins nucleate the assembly of unbranched filaments 

2. Arp2/3 complex nucleates the assembly of branched actin networks

TLS Online TPP Program

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#XL - R Botany

Cdc25B is act as a starter phosphatase that initiates CDK1 activation

Cdc25C is the workhorse phosphatase that activates the vast majority of cyclin-CDK1 complexes

TLS Online TPP Program

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#XL - R Botany

TLS Online TPP Program

#Id: 8869

#XL - R Botany

Yeast cells with a defective wee1+ gene activate mitotic CDKs prematurely and premature entry into mitosis (smaller than normal cells

TLS Online TPP Program

#Id: 8870

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Fission yeast cells carrying a CDK1 mutation in which the tyrosine-15 residue is replaced by phenylalanine

show the same premature mitotic CDK activation and entry into mitosis.

TLS Online TPP Program

#Id: 8871

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Until Mitotic CDKs is not active, the activatory protein phosphatase, Cdc25, is phosphorylated, bound and inhibited by phosphoserine/threonine-binding protein 14-3-3.

TLS Online TPP Program

#Id: 8872

#XL - R Botany

The entire process of mitotic CDKs activation and entry into mitosis involves two positive feedback loops and coordination between events at the centrosome, in the cytoplasm, and in the nucleus.