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Nat Cell Biol 2006 Oct 01;810:1084-94. doi: 10.1038/ncb1472.
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Meiotic regulation of the CDK activator RINGO/Speedy by ubiquitin-proteasome-mediated processing and degradation.

Gutierrez GJ , Vögtlin A , Castro A , Ferby I , Salvagiotto G , Ronai Z , Lorca T , Nebreda AR .

Xenopus RINGO/Speedy (XRINGO) is a potent inducer of oocyte meiotic maturation that can directly activate Cdk1 and Cdk2. Here, we show that endogenous XRINGO protein accumulates transiently during meiosis I entry and then is downregulated. This tight regulation of XRINGO expression is the consequence of two interconnected mechanisms: processing and degradation. XRINGO processing involves recognition of at least three distinct phosphorylated recognition motifs by the SCF(betaTrCP) ubiquitin ligase, followed by proteasome-mediated limited degradation, resulting in an amino-terminal XRINGO fragment. XRINGO processing is directly stimulated by several kinases, including protein kinase A and glycogen synthase kinase-3beta, and may contribute to the maintenance of G2 arrest. On the other hand, XRINGO degradation after meiosis I is mediated by the ubiquitin ligase Siah-2, which probably requires phosphorylation of XRINGO on Ser 243 and may be important for the omission of S phase at the meiosis-I-meiosis-II transition in Xenopus oocytes.

PubMed ID: 16964245
Article link: Nat Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: btrc cdk1 cdk2 gys1 siah1 spdya