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Protein phosphatase 2A interacts with the Src kinase substrate p130(CAS).
1Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, NY 11794-8661, USA.
Oncogene
|October 11, 2001
Summary
Protein phosphatase 2A (PP2A) interacts with Cas, a Src substrate. PP2A dephosphorylates Cas, suggesting a role in cell cycle regulation and Cas dephosphorylation.
Area of Science:
- Cellular Biology
- Molecular Biology
- Signal Transduction
Background:
- Cas (Crk-associated substrate) is a key substrate in Src-mediated signaling pathways.
- Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase involved in diverse cellular processes.
- v-Src, a viral tyrosine kinase, regulates cell growth and transformation through phosphorylation events.
Purpose of the Study:
- To investigate the interaction between Cas and PP2A.
- To elucidate the role of v-Src activation in modulating the Cas-PP2A association.
- To determine PP2A's function in Cas phosphorylation during the cell cycle.
Main Methods:
- Utilized cells expressing a temperature-sensitive v-Src mutant.
- Performed co-immunoprecipitation and pull-down assays to assess protein interactions.
- Employed Microcystin and okadaic acid as PP2A inhibitors.
- Analyzed tyrosine and serine/threonine phosphorylation levels of Cas and v-Src.
Main Results:
- v-Src activation increased tyrosine phosphorylation of v-Src and Cas, and their association.
- v-Src-PP2A association decreased upon v-Src activation, while Cas-PP2A association increased.
- PP2A inhibition (okadaic acid) augmented Cas serine/threonine phosphorylation, particularly at mitosis.
- PP2A demonstrated in vitro dephosphorylation of serine residues on Cas.
Conclusions:
- PP2A directly associates with Cas.
- v-Src signaling influences the interaction between PP2A and Cas.
- PP2A plays a role in the cell cycle-specific dephosphorylation of Cas.