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Updated: May 14, 2026
12:26
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Phosphate-activated cyclin-dependent kinase stabilizes G1 cyclin to trigger cell cycle entry
1Departament de Ciències Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Internacional de Catalunya, Barcelona, Catalunya, Spain.
Molecular and Cellular Biology
|January 24, 2013
Summary
Phosphate availability regulates cell cycle entry by controlling Cln3 cyclin stability via Pho85 kinase activity in yeast. This Pho85-Cln3 interaction is crucial for proper G1 arrest and cell survival.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- G1 cyclins and cyclin-dependent kinases (CDKs) activate cell cycle entry.
- Mechanisms controlling cyclin stability for cell cycle regulation remain unclear.
Purpose of the Study:
- Investigate how phosphate availability influences cell cycle entry.
- Determine the role of Pho85 kinase in regulating Cln3 cyclin stability and cell cycle progression.
Main Methods:
- Utilized Saccharomyces cerevisiae (yeast) as a model organism.
- Examined Cln3 cyclin stability and protein interactions in yeast strains with varying Pho85 activity.
- Analyzed the impact of specific CLN3 mutations on cell cycle progression and survival.
Main Results:
- Phosphate deficiency downregulates Cln3 cyclin, causing G1 arrest in yeast.
- Low Pho85 kinase activity diminishes Cln3 stability; Pho85 directly phosphorylates Cln3.
- Mutations preventing Pho85 phosphorylation of Cln3 lead to high Cln3 levels, impaired G1 arrest, and premature cell death.
Conclusions:
- Cln3 is a direct molecular target of Pho85 kinase.
- Pho85-mediated regulation of Cln3 stability controls cell cycle entry in response to phosphate availability.
- This pathway is essential for yeast cell cycle progression and survival under nutrient fluctuations.
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