Mutational analysis of sites in the translational regulator, PHAS-I, that are selectively phosphorylated by mTOR.
Results obtained with PHAS-I proteins having Ser to Ala mutations in the five known phosphorylation sites indicate that mTOR preferentially phosphorylates Thr36 and Thr45. The effects of phosphorylating these sites on eIF4E binding were assessed in a far-Western analysis with a labeled eIF4E probe. Phosphorylation of Thr36 only slightly attenuated binding of PHAS-I to eIF4E, while phosphorylation of Thr45 markedly inhibited binding. Phosphorylation of neither site affected the electrophoretic mobility of the protein, indicating that results of studies that rely solely on a gel-shift assay to assess changes in PHAS-I phosphorylation must be interpreted with caution.
Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908, USA.
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Yang
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Brunn
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Lawrence
D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins; D004252:DNA Mutational Analysis; D039561:Eukaryotic Initiation Factor-4E; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases; D013379:Substrate Specificity; D058570:TOR Serine-Threonine Kinases; D013912:Threonine / Q000378:metabolism
D002352:Carrier Proteins; D039561:Eukaryotic Initiation Factor-4E; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D013912:Threonine; D011494:Protein Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D058570:TOR Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases