SHP1 

Binding of an SH2 domain to a phosphotyrosine in the activated receptor unmasks its phosphatase catalytic site

TLS Online TPP Program

#Id: 8847

#XL - R Botany

When CDK activity is low= helicases are loaded in G1

When CDK activity is high= helicases are activated in

S, G2 & M

TLS Online TPP Program

#Id: 8848

#XL - R Botany

TLS Online TPP Program

#Id: 8849

#XL - R Botany

Phosphorylation of MCM helicase activators by G1/S phase CDKs and S phase CDKs, prevents reloading of MCM helicases (ensuring that replication from each origin occurs only once during each cell cycle)

TLS Online TPP Program

#Id: 8850

#XL - R Botany

Geminin 

a small protein,, that contributes to the inhibition of re-initiation at origins until cells complete a full cell cycle.

TLS Online TPP Program

#Id: 8851

#XL - R Botany

Geminin is expressed in late G1; it binds to and inhibits Cdt1 preventing reloading of the MCM helicase.

TLS Online TPP Program

#Id: 8852

#XL - R Botany

Geminin contains a destruction box at its N-terminus that is recognized by APC/Ccdh1, causing it to be ubiquitinylated in late anaphase and degraded by proteasomes.