Vadysirisack, Douangsone D.Douangsone D.VadysirisackChen, Eric S.-W.Eric S.-W.ChenZhang, ZhaoxiaZhaoxiaZhangTsai, Ming-DawMing-DawTsaiChang, Geen-DongGeen-DongChangJhiang, Sissy M.Sissy M.Jhiang2009-07-292018-07-062009-07-292018-07-06200700219258http://ntur.lib.ntu.edu.tw//handle/246246/163065https://www.scopus.com/inward/record.uri?eid=2-s2.0-37549070369&doi=10.1074%2fjbc.M706817200&partnerID=40&md5=a7914f7cf43fb15e21ab50c7be1915dcThe Na+/I- symporter (NIS)-mediated iodide uptake activity is the basis for targeted radioiodide ablation of thyroid cancers. Although it has been shown that NIS protein is phosphorylated, neither the in vivo phosphorylation sites nor their functional significance has been reported. In this study, Ser-43, Thr-49, Ser-227, Thr-577, and Ser-581 were identified as in vivo NIS phosphorylation sites by mass spectrometry. Kinetic analysis of NIS mutants of the corresponding phosphorylated amino acid residue indicated that the velocity of iodide transport of NIS is modulated by the phosphorylation status of Ser-43 and Ser-581. We also found that the phosphorylation status of Thr-577 may be important for NIS protein stability and that the phosphorylation status of Ser-227 is functionally silent. Thr-49 appears to be critical for proper local structure/conformation of NIS because mutation of Thr-49 to alanine, aspartic acid, or serine results in reduced NIS activity without alterations in total or cell surface NIS protein levels. Taken together, we showed that NIS protein levels and functional activity could be modulated by phosphorylation through distinct mechanisms. ? 2007 by The American Society for Biochemistry and Molecular Biology, Inc.application/pdf752325 bytesapplication/pdfen-US[SDGs]SDG3Amino acids; Mass spectrometry; Proteins; Sodium compounds; Tumors; Distinct mechanisms; Sodium iodide symporter; Phosphorylation; alanine; aspartic acid; mutant protein; serine; sodium iodide symporter; threonine; amino acid substitution; article; human; human cell; in vivo study; mass spectrometry; mutation; nonhuman; priority journal; protein conformation; protein function; protein phosphorylation; protein stability; protein structure; rat; thyroid cancer; Amino Acid Substitution; Animals; Cell Line; Humans; Iodides; Ion Transport; Mutation, Missense; Phosphorylation; Protein Processing, Post-Translational; Rats; Symporters; Thyroid Neoplasmsjournal article10.1074/jbc.M706817200179137072-s2.0-37549070369http://ntur.lib.ntu.edu.tw/bitstream/246246/163065/1/24.pdf