Identification and characterization of a putative human iodide transporter located at the apical membrane of thyrocytes.
Iodide transport by thyrocytes is a two step process involving transporters located either in the basal or in the apical membranes of the cell. The sodium iodide symporter (NIS) is localized in the basolateral membrane facing the bloodstream and mediates iodide accumulation into thyrocytes. Pendrin has been proposed as an apical transporter. In order to identify new iodide transporters, we developed a PCR cloning strategy based on NIS sequence homologies. From a human kidney cDNA library, we characterized a gene, located on chromosome 12q23, that encodes a 610 amino acid protein sharing 46% identity (70% similarity) with the human NIS. Functional analysis of the protein expressed in mammalian cells indicates that it catalyzes a passive iodide transport. The protein product was immunohistochemically localized at the apical pole of the thyroid cells facing the colloid lumen. These results suggest that this new identified protein mediates iodide transport from the thyrocyte into the colloid lumen through the apical membrane. It was designated hAIT for human Apical Iodide Transporter.
Rodriguez
Anne-Marie
AM
Commissariat à l'Energie Atomique LRC16V, University Nice Sophia-Antipolis, CNRS UMR6078, F-06230 Villefranche-sur-Mer, France.
Perron
Barbara
B
Lacroix
Ludovic
L
Caillou
Bernard
B
Leblanc
Gérard
G
Schlumberger
Martin
M
Bidart
Jean-Michel
JM
Pourcher
Thierry
T
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D027682:Cation Transport Proteins; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D027501:Monocarboxylic Acid Transporters; D017386:Sequence Homology, Amino Acid; D027981:Symporters / Q000235:genetics* / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*; D014018:Tissue Distribution; D000099209:Sodium-Iodide Symporters
D027682:Cation Transport Proteins; D018076:DNA, Complementary; D027501:Monocarboxylic Acid Transporters; D027981:Symporters; D000099209:Sodium-Iodide Symporters; C476760:SLC5A8 protein, human