cdc2 kinase-mediated phosphorylation of splicing factor SF2/ASF.
SR proteins are a family of splicing factors which are important components of spliceosomes. Recent studies suggested that phosphorylation of SR protein might be a key event for the regulation of pre-mRNA splicing and is prevalent in metaphase cells. To investigate the role of cdc2 kinase in cell cycle-dependent phosphorylation of SR protein, we examined its phosphorylation of SF2/ASF, a representative SR protein. SF2/ASF was phosphorylated both by recombinant cdc2 kinase, a cdc2-cyclin B complex, and by cdc2 kinase immunoprecipitated from G2/M phase HeLa cells. In vitro phosphorylation and phosphopeptide mapping of several mutant proteins revealed that cdc2 kinase specifically phosphorylates the RS domain of SF2/ASF with serines 227, 238 and presumably 199 as major phosphorylation sites. These findings suggest the possibility that cdc2 kinase takes part in the cell cycle-dependent phosphorylation of SR protein which regulates the function of spliceosomes.
Okamoto
Y
Y
First Department of Surgery, Nagoya University School of Medicine, Japan.
Onogi
H
H
Honda
R
R
Yasuda
H
H
Wakabayashi
T
T
Nimura
Y
Y
Hagiwara
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D016203:CDC2 Protein Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D017931:DNA Primers / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D017354:Point Mutation; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D000068103:Serine-Arginine Splicing Factors; D017381:Spliceosomes / Q000378:metabolism
D017931:DNA Primers; D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000068103:Serine-Arginine Splicing Factors; D016203:CDC2 Protein Kinase