| pmid | 10913169 | ||||
|---|---|---|---|---|---|
| title | Cks1 is required for G(1) cyclin-cyclin-dependent kinase activity in budding yeast. | ||||
| authors |
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| journal | Mol Cell Biol | ||||
| year | 2000 | ||||
| full_text_available | false | ||||
| full_text_extraction_method | html_abstract_only | ||||
| pmcid | PMC86063 | ||||
| doi | 10.1128/MCB.20.16.5858-5864.2000 |
Authors: Reynard GJ, Reynolds W, Verma R, Deshaies RJ Journal: Mol Cell Biol (2000) DOI: 10.1128/MCB.20.16.5858-5864.2000 PMC: PMC86063
- Mol Cell Biol. 2000 Aug;20(16):5858-64. doi: 10.1128/MCB.20.16.5858-5864.2000.
Cks1 is required for G(1) cyclin-cyclin-dependent kinase activity in budding yeast.
Reynard GJ(1), Reynolds W, Verma R, Deshaies RJ.
Author information: (1)Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
p13(suc1) (Cks) proteins have been implicated in the regulation of cyclin-dependent kinase (CDK) activity. However, the mechanism by which Cks influences the function of cyclin-CDK complexes has remained elusive. We show here that Cks1 is required for the protein kinase activity of budding yeast G(1) cyclin-CDK complexes. Cln2 and Cdc28 subunits coexpressed in baculovirus-infected insect cells fail to exhibit protein kinase activity towards multiple substrates in the absence of Cks1. Cks1 can both stabilize Cln2-Cdc28 complexes and activate intact complexes in vitro, suggesting that it plays multiple roles in the biogenesis of active G(1) cyclin-CDK complexes. In contrast, Cdc28 forms stable, active complexes with the B-type cyclins Clb4 and Clb5 regardless of whether Cks1 is present. The levels of Cln2-Cdc28 and Cln3-Cdc28 protein kinase activity are severely reduced in cks1-38 cell extracts. Moreover, phosphorylation of G(1) cyclins, which depends on Cdc28 activity, is reduced in cks1-38 cells. The role of Cks1 in promoting G(1) cyclin-CDK protein kinase activity both in vitro and in vivo provides a simple molecular rationale for the essential role of CKS1 in progression through G(1) phase in budding yeast.
DOI: 10.1128/MCB.20.16.5858-5864.2000 PMCID: PMC86063 PMID: 10913169 [Indexed for MEDLINE]
Abstract
p13 suc1 (Cks) proteins have been implicated in the regulation of cyclin-dependent kinase (CDK) activity. However, the mechanism by which Cks influences the function of cyclin-CDK complexes has remained elusive. We show here that Cks1 is required for the protein kinase activity of budding yeast G 1 cyclin-CDK complexes. Cln2 and Cdc28 subunits coexpressed in baculovirus-infected insect cells fail to exhibit protein kinase activity towards multiple substrates in the absence of Cks1. Cks1 can both stabilize Cln2-Cdc28 complexes and activate intact complexes in vitro, suggesting that it plays multiple roles in the biogenesis of active G 1 cyclin-CDK complexes. In contrast, Cdc28 forms stable, active complexes with the B-type cyclins Clb4 and Clb5 regardless of whether Cks1 is present. The levels of Cln2-Cdc28 and Cln3-Cdc28 protein kinase activity are severely reduced in cks1-38 cell extracts. Moreover, phosphorylation of G 1 cyclins, which depends on Cdc28 activity, is reduced in cks1-38 cells. The role of Cks1 in promoting G 1 cyclin-CDK protein kinase activity both in vitro and in vivo provides a simple molecular rationale for the essential role of CKS1 in progression through G 1 phase in budding yeast.