Triggering of cyclin degradation in interphase extracts of amphibian eggs by cdc2 kinase

• Published in: Nature (London) 1990-07, Vol.346 (6282), p.379-382
• Main Authors: Félix, Marie-Anne, Labbé, Jean-Claude, Dorée, Marcel, Hunt, Tim, Karsenti, Eric
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biochemistry; Biodegradation; Biological and medical sciences; Cdc2 protein; CDC2 Protein Kinase; Cell cycle, cell proliferation; Cell physiology; Cellular biology; Control theory; Cyclins; Dephosphorylation; Destruction; Eggs; Embryos; Feedback loops; Fundamental and applied biological sciences. Psychology; Homology; Humanities and Social Sciences; Interphase; Invertebrate Hormones - metabolism; Kinases; Kinetics; letter; Medical research; Mitosis; Models, Biological; Molecular and cellular biology; Molecular Sequence Data; multidisciplinary; Negative feedback; Oocytes - cytology; Oocytes - physiology; Peptides; Phosphoproteins - isolation & purification; Phosphoproteins - metabolism; Phosphorylation; Post-translation; Protein kinase C; Protein Kinases - metabolism; Proteins; Proteolysis; Science; Science (multidisciplinary); Starfish; Threonine; Tyrosine; Xenopus; Yeast; Yeasts
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/346379a0

THE cell cycles of early Xenopus embryos consist of a rapid succession of alternating S and M phases 1 . These cycles are controlled by the activity of a protein kinase complex (cdc2 kinase) which contains two subunits. One subunit is encoded by the frog homologue of the fission yeast cdc2 + gene, p34 cdc2 (ref. 2) and the other is a cyclin 3 . The concentration of cyclins follows a sawtooth oscillation because they accumulate in interphase and are destroyed abruptly during mitosis 3 . The association of cyclin and p34 cdc2 (refs 4–7) is not sufficient for activation of cdc2 kinase, however; dephosphorylation of key tyrosine and threonine residues of p34 cdc2 is necessary to turn on its kinase activity 8–11 . The activity of cdc2 kinase is thus regulated by a combination of translational and post-translational mechanisms. The loss of cdc2 kinase activity at the end of mitosis depends on the destruction of the cyclin subunits 3,4,12,13 . It has been suggested that this destruction is induced by cdc2 kinase itself, thereby providing a negative feedback loop to terminate mitosis 14,15 . Here we report direct experimental evidence for this idea by showing that cyclin proteolysis can be triggered by adding cdc2 kinase to a cell-free extract of interphase Xenopus eggs.