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cdc2 kinase-mediated phosphorylation of splicing factor SF2/ASF
1First Department of Surgery, Nagoya University School of Medicine, Japan.
Biochemical and Biophysical Research Communications
|September 10, 1998
Summary
cdc2 kinase phosphorylates SF2/ASF, an SR protein, at specific sites within its RS domain. This phosphorylation, occurring during the cell cycle, suggests cdc2 kinase regulates spliceosome function via SR protein modification.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- SR proteins are crucial splicing factors in spliceosomes.
- Phosphorylation of SR proteins is linked to pre-mRNA splicing regulation.
- SR protein phosphorylation is notably prevalent in metaphase cells.
Purpose of the Study:
- To investigate the role of cdc2 kinase in the cell cycle-dependent phosphorylation of SR proteins.
- To examine the specific phosphorylation of SF2/ASF, a representative SR protein, by cdc2 kinase.
Main Methods:
- In vitro phosphorylation assays using recombinant cdc2 kinase and cdc2-cyclin B complex.
- Immunoprecipitation of cdc2 kinase from G2/M phase HeLa cells.
- In vitro phosphorylation and phosphopeptide mapping of SF2/ASF mutants.
Main Results:
- SF2/ASF was phosphorylated by both recombinant and immunoprecipitated cdc2 kinase.
- cdc2 kinase specifically phosphorylates the RS domain of SF2/ASF.
- Serines 227 and 238, and presumably 199, were identified as major phosphorylation sites.
Conclusions:
- cdc2 kinase participates in the cell cycle-dependent phosphorylation of SR proteins.
- This phosphorylation event likely regulates spliceosome function.
- The findings provide insight into the cell cycle control of pre-mRNA splicing.