Yang D, Brunn G J, Lawrence J C
Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908, USA.
FEBS Lett. 1999 Jun 25;453(3):387-90. doi: 10.1016/s0014-5793(99)00762-0.
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.
在五个已知磷酸化位点具有丝氨酸到丙氨酸突变的PHAS-I蛋白所获得的结果表明，mTOR优先磷酸化苏氨酸36和苏氨酸45。在使用标记的eIF4E探针的远缘Western分析中评估了这些位点磷酸化对eIF4E结合的影响。仅苏氨酸36的磷酸化略微减弱了PHAS-I与eIF4E的结合，而苏氨酸45的磷酸化则显著抑制了结合。两个位点的磷酸化均未影响该蛋白的电泳迁移率，这表明仅依靠凝胶迁移试验来评估PHAS-I磷酸化变化的研究结果必须谨慎解释。
