Mechanisms and regulation of the degradation of cyclin B

Philos Trans R Soc Lond B Biol Sci. 1999 Sep 29;354(1389):1571-5; discussion 1575-6. doi: 10.1098/rstb.1999.0500.

Abstract

The degradation of the cyclin B subunit of protein kinase Cdk1/cyclin B is required for inactivation of the kinase and exit from mitosis. Cyclin B is degraded by the ubiquitin pathway, a system involved in most selective protein degradation in eukaryotic cells. In this pathway, proteins are targeted for degradation by ligation to ubiquitin, a process carried out by the sequential action of three enzymes: the ubiquitin-activating enzyme E1, a ubiquitin-carrier protein E2 and a ubiquitin-protein ligase E3. In the system responsible for cyclin B degradation, the E3-like function is carried out by a large complex called cyclosome or anaphase-promoting complex (APC). In the early embryonic cell cycles, the cyclosome is inactive in the interphase, but becomes active at the end of mitosis. Activation requires phosphorylation of the cyclosome/APC by protein kinase Cdk1/cyclin B. The lag kinetics of cyclosome activation may be explained by Suc1-assisted multiple phosphorylations of partly phosphorylated complex. The presence of a Fizzy/Cdc20-like protein is necessary for maximal activity of the mitotic form of cyclosome/APC in cyclin-ubiquitin ligation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Anaphase-Promoting Complex-Cyclosome
  • Animals
  • Cell Cycle
  • Cell Cycle Proteins / metabolism
  • Cyclin B / metabolism*
  • Drosophila
  • Drosophila Proteins
  • Ligases / metabolism*
  • Ubiquitin-Protein Ligase Complexes*
  • Ubiquitin-Protein Ligases
  • Xenopus

Substances

  • Cell Cycle Proteins
  • CycB protein, Drosophila
  • Cyclin B
  • Drosophila Proteins
  • Ubiquitin-Protein Ligase Complexes
  • Anaphase-Promoting Complex-Cyclosome
  • Ubiquitin-Protein Ligases
  • Ligases