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Mutational analysis of sites in the translational regulator, PHAS‐I, that are selectively phosphorylated by mTOR
Author(s) -
Yang Daqing,
Brunn Gregory J,
Lawrence John C
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)00762-0
Subject(s) - phosphorylation , protein phosphorylation , chemistry , regulator , pi3k/akt/mtor pathway , biochemistry , protein kinase a , signal transduction , gene
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.