Substrate recognition and ubiquitination of SCFSkp2/Cks1 ubiquitin-protein isopeptide ligase.
J Biol Chem
; 282(21): 15462-70, 2007 May 25.
Article
em En
| MEDLINE
| ID: mdl-17409098
ABSTRACT
p27, an important cell cycle regulator, blocks the G(1)/S transition in cells by binding and inhibiting Cdk2/cyclin A and Cdk2/cyclin E complexes (Cdk2/E). Ubiquitination and subsequent degradation play a critical role in regulating the levels of p27 during cell cycle progression. Here we provide evidence suggesting that both Cdk2/E and phosphorylation of Thr(187) on p27 are essential for the recognition of p27 by the SCF(Skp2/Cks1) complex, the ubiquitin-protein isopeptide ligase (E3). Cdk2/E provides a high affinity binding site, whereas the phosphorylated Thr(187) provides a low affinity binding site for the Skp2/Cks1 complex. Furthermore, binding of phosphorylated p27/Cdk2/E to the E3 complex showed positive cooperativity. Consistently, p27 is also ubiquitinated in a similarly cooperative manner. In the absence of p27, Cdk2/E and Cks1 increase Skp2 phosphorylation. This phosphorylation enhances Skp2 auto-ubiquitination, whereas p27 inhibits both phosphorylation and auto-ubiquitination of Skp2.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Transporte
/
Processamento de Proteína Pós-Traducional
/
Quinases Ciclina-Dependentes
/
Ubiquitina-Proteína Ligases
/
Proteínas Quinases Associadas a Fase S
/
Complexos Multiproteicos
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article