Publication Date:
1997-10-23
Description:
G1 cyclin-dependent kinase (Cdk)-triggered degradation of the S-phase Cdk inhibitor Sic1p has been implicated in the transition from G1 to S phase in the cell cycle of budding yeast. A multidimensional electrospray mass spectrometry technique was used to map G1 Cdk phosphorylation sites in Sic1p both in vitro and in vivo. A Sic1p mutant lacking three Cdk phosphorylation sites did not serve as a substrate for Cdc34p-dependent ubiquitination in vitro, was stable in vivo, and blocked DNA replication. Moreover, purified phosphoSic1p was ubiquitinated in cyclin-depleted G1 extract, indicating that a primary function of G1 cyclins is to tag Sic1p for destruction. These data suggest a molecular model of how phosphorylation and proteolysis cooperate to bring about the G1/S transition in budding yeast.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Verma, R -- Annan, R S -- Huddleston, M J -- Carr, S A -- Reynard, G -- Deshaies, R J -- R01 GM52466-01/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Oct 17;278(5337):455-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology, Box 156-29, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9334303" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Sequence
;
Anaphase-Promoting Complex-Cyclosome
;
Cyclin G
;
Cyclin-Dependent Kinase Inhibitor Proteins
;
Cyclin-Dependent Kinases/*metabolism
;
Cyclins/*metabolism
;
DNA Replication
;
Enzyme Inhibitors/metabolism
;
Fungal Proteins/*metabolism
;
G1 Phase
;
Ligases/metabolism
;
Molecular Sequence Data
;
Mutagenesis
;
Phenotype
;
Phosphopeptides/metabolism
;
Phosphorylation
;
Recombinant Fusion Proteins/metabolism
;
*S Phase
;
*Saccharomyces cerevisiae Proteins
;
*Ubiquitin-Protein Ligase Complexes
;
Ubiquitin-Protein Ligases
;
Ubiquitins/metabolism
;
Yeasts/*cytology/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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