HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Accepted manuscript (PDF) Supplementary figures All Versions of this Article: JOE-08-0249v1 199/2/213    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wu, S.-L. Articles by Hsiang, C.-Y. Search for Related Content PubMed PubMed Citation Articles by Wu, S.-L. Articles by Hsiang, C.-Y.

S Wu, Taichung, 40402, Taiwan - Republic of China
T Ho, Taichung, Taiwan - Republic of China
J Liang, China Medical University Hostipal, Taichung, Taiwan - Republic of China
C Hsiang, China Medical University, Taichung, Taiwan - Republic of China

Correspondence: Shih-Lu Wu, Email: cyhsiang{at}mail.cmu.edu.tw

Abstract

The sodium/iodide symporter (NIS), a transmembrane glycoprotein principally in the thyroid gland, is responsible for the accumulation of iodide necessary for thyroid hormones. Our previous study indicated that a novel exon 6 deletion (residues 233 to 280) in NIS loses the iodide uptake activity. Herein we characterized the role of His-226 in iodide transport of NIS. His-226, a highly conserved extracellular residue among NIS homologs, was replaced with alanine, aspartic acid, glutamic acid, or lysine. All the NIS mutants were expressed normally in the cells and targeted correctly to the plasma membrane. However, all the mutants displayed severe defects in iodide uptake, suggesting that His-226 was critical for iodide uptake. Kinetic analysis further showed that mutation at His-226 led to a dramatic decrease in Vmax. These findings suggested that the decreased levels of iodide uptake activity of NIS mutants resulted from lower catalytic rates. In conclusion, our data first identified the involvement of extracellular charged amino acid residue in the iodide uptake ability of NIS.

This article has been cited by other articles:

				A. Bizhanova and P. Kopp The Sodium-Iodide Symporter NIS and Pendrin in Iodide Homeostasis of the Thyroid Endocrinology, March 1, 2009; 150(3): 1084 - 1090. [Abstract] [Full Text] [PDF]