Cell-free degradation of p27(kip1), a G1 cyclin-dependent kinase inhibitor, is dependent on CDK2 activity and the proteasome Journal Article
| Authors: | Nguyen, H.; Gitig, D. M.; Koff, A. |
| Article Title: | Cell-free degradation of p27(kip1), a G1 cyclin-dependent kinase inhibitor, is dependent on CDK2 activity and the proteasome |
| Abstract: | Entry into S phase is dependent on the coordinated activation of CDK4,6 and CDK2 kinases. Once a cell commits to S phase, there must be a mechanism to ensure the irreversibility of this decision. The activity of these kinases is inhibited by their association with p27. In many cells, p27 plays a major role in the withdrawal from the cell cycle in response to environmental cues. Thus, it is likely that p27 is a target of the machinery required to ensure the irreversibility of S-phase entry. We have been interested in understanding the mechanisms regulating p27 at the G1/S transition. In this report, we define a cell-free degradation system which faithfully recapitulates the cell cycle phase-specific degradation of p27. We show that this reaction is dependent on active CDK2 activity, suggesting that CDK2 activity is directly required for p27 degradation. In addition to CDK2, other S-phase-specific factors are required for p27 degradation. At least some of these factors are ubiquitin and proteasome dependent. We discuss the relationships between CDK2 activity, ubiquitin-dependent, and possibly ubiquitin-independent proteasomal activities in S-phase extracts as related to p27. |
| Keywords: | signal transduction; polymerase chain reaction; phenotype; cell cycle proteins; cell cycle; cell cycle s phase; proteasome; enzyme inhibition; proteasome endopeptidase complex; protein degradation; protein binding; enzyme activity; hela cells; amino terminal sequence; cell culture; enzyme inhibitors; protein-serine-threonine kinases; protein p27; cyclin-dependent kinase inhibitor p27; tumor suppressor proteins; recombinant proteins; immunoprecipitation; immunoblotting; base sequence; cycline; multienzyme complexes; cyclin-dependent kinases; cyclins; phosphotransferase; g1 phase; s phase; polyacrylamide gel electrophoresis; stoichiometry; ubiquitins; xenopus; cyclin-dependent kinase 2; microtubule-associated proteins; cysteine endopeptidases; cell-free system; oligonucleotide probes; cdc2-cdc28 kinases; humans; priority journal; article; dna probe |
| Journal Title: | Molecular and Cellular Biology |
| Volume: | 19 |
| Issue: | 2 |
| ISSN: | 0270-7306 |
| Publisher: | American Society for Microbiology |
| Date Published: | 1999-02-01 |
| Start Page: | 1190 |
| End Page: | 1201 |
| Language: | English |
| PUBMED: | 9891053 |
| PROVIDER: | scopus |
| PMCID: | PMC116048 |
| DOI: | 10.1128/MCB.19.2.1190 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 16 August 2016 -- Source: Scopus |
