Cybip, a starfish cyclin B-binding protein, is involved in meiotic M-phase exit.
We designed a screen to identify starfish oocyte proteins able to bind monomeric cyclin B by affinity chromatography on a cyclin B splice variant displaying low affinity for cdc2. We identified a 15kDa protein previously described as a cdk-binding protein [Biochim. Biophys. Acta Mol. Cell Res. 1589 (2002) 219-231]. Cybip is encoded by a single polymorphic gene and the native protein is matured by cleaving a signal peptide. We firmly establish the fact that it is a true cyclin B-binding protein, since the recombinant protein binds recombinant cyclin B in absence of any cdk. Finally, we show that the microinjection of GST-cybip, and of anti-cybip antibody, in maturing starfish oocytes, inhibits H1 kinase and MPF inactivation, and first polar body emission.
Offner
Nicolas
N
UMR 7628, Laboratoire Arago, BP 44, F-66651 Banyuls sur Mer Cedex, France.
Derancourt
Jean
J
Lozano
Jean Claude
JC
Schatt
Philippe
P
Picard
André
A
Peaucellier
Gérard
G
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002846:Chromatography, Affinity; D019926:Cyclin B / Q000378:metabolism*; D005260:Female; D016200:Maturation-Promoting Factor / Q000378:metabolism; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D011110:Polymorphism, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013215:Starfish / Q000166:cytology / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D019926:Cyclin B; D020033:Protein Isoforms; D016200:Maturation-Promoting Factor