Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-24654
EMBO J 1991 Aug 01;108:2087-93. doi: 10.1002/j.1460-2075.1991.tb07741.x.
Show Gene links Show Anatomy links

Degradation of the proto-oncogene product p39mos is not necessary for cyclin proteolysis and exit from meiotic metaphase: requirement for a Ca(2+)-calmodulin dependent event.

Lorca T , Galas S , Fesquet D , Devault A , Cavadore JC , Dorée M .


???displayArticle.abstract???
Exit from M phase, which requires cyclin degradation, is prevented from occurring in unfertilized eggs of vertebrates arrested at second meiotic metaphase due to a cytostatic factor recently identified as p39mos, the product of the proto-oncogene c-mos. Calpain can destroy both p39mos and cyclin in vitro in extracts prepared from metaphase-arrested Xenopus eggs, but only when free Ca2+ concentration is raised to the millimolar range. When free Ca2+ concentration is raised for only 30 s to the micromolar range, as occurs in physiological conditions after fertilization, cyclin degradation is induced, byt p39mos is not degraded. Cyclin proteolysis at micromolar free Ca2+, is not inhibited by calpastatin, and therefore does not involve calpain. A cyclin mutant modified in the destruction box is found to be resistant at micromolar, but not millimolar free Ca2+, suggesting that the ubiquitin pathway mediates cyclin degradation at micromolar Ca2+ concentration whereas calpain is involved at the millimolar level. A synthetic peptide which binds Ca(2+)-calmodulin with high affinity suppresses cyclin degradation at micromolar but not millimolar free Ca2+, and this only when it is present in the extract during the first 30 s after raising free Ca2+ concentration. The inhibition of the cyclin degradation pathway by the Ca(2+)-calmodulin binding peptide can be overcome by adding calmodulin. These results strongly suggest that a Ca(2+)-calmodulin process is required as an early event following fertilization to release the cyclin degradation pathway from inhibition in metaphase-arrested eggs. In contrast, p39mos degradation is not required.

???displayArticle.pubmedLink??? 1829675
???displayArticle.pmcLink??? PMC452893
???displayArticle.link??? EMBO J


Species referenced: Xenopus
Genes referenced: cast mos

References [+] :
Autric, Large-scale purification and characterization of calmodulin from ram testis: its metal-ion-dependent conformers. 1980, Pubmed