Phosphorylation by SR kinases regulates the binding of PTB-associated splicing factor (PSF) to the pre-mRNA polypyrimidine tract.
PSF (PTB-associated splicing factor) is a multi-functional protein that participates in transcription and RNA processing. While phosphorylation of PSF has been shown to be important for some functions, the sites and the kinases involved are not well understood. Although PSF does not contain a typical RS domain, we report here that PSF is phosphorylated in vivo to generate an epitope(s) that can be recognized by a monoclonal antibody specific for phosphorylated RS motifs within SR proteins. PSF can be phosphorylated by human and yeast SR kinases in vivo and in vitro at an isolated RS motif within its N terminus. A functional consequence of SR phosphorylation of PSF is to inhibit its binding to the 3' polypyrimidine tract of pre-mRNA. These results indicate that PSF is a substrate of SR kinases whose phosphorylation regulates its RNA binding capacity and ultimate biological function.
Huang
Ching-Jung
CJ
Section of Molecular Genetics and Microbiology and Institute for Cellular and Molecular Biology, University of Texas, 1 University Station, A5000 Austin, TX 78712, United States.
Tang
Zhaohua
Z
Lin
Ren-Jang
RJ
Tucker
Philip W
PW
D000595:Amino Acid Sequence; D000818:Animals; D045163:Antibodies, Phospho-Specific / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D038941:Polypyrimidine Tract-Binding Protein / Q000276:immunology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011743:Pyrimidines / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism*; D013379:Substrate Specificity
D045163:Antibodies, Phospho-Specific; D011743:Pyrimidines; D012322:RNA Precursors; D038941:Polypyrimidine Tract-Binding Protein; C403617:Dsk1 protein kinase; C087728:SRPK1 protein, human; D017346:Protein Serine-Threonine Kinases; C030986:pyrimidine