Cloning and characterization of the thyroid iodide transporter

G Dai, O Levy, N Carrasco - Nature, 1996 - nature.com
G Dai, O Levy, N Carrasco
Nature, 1996nature.com
IODIDE (I-) is an essential constituent of the thyroid hormones T3 and T4, and is
accumulated by the thyroid. The transport of iodide, the first step in thyroid hormogenesis, is
catalysed by the Na+/I-symporter, an intrinsic membrane protein that is crucial for the
evaluation, diagnosis and treatment of thyroid disorders. Although several other important
thyroid proteins involved in hormogenesis have been characterized, the Na+/I-symporter
has not. Here we report the isolation of a complementary DNA clone that encodes this …
Abstract
IODIDE (I-) is an essential constituent of the thyroid hormones T3 and T4, and is accumulated by the thyroid. The transport of iodide, the first step in thyroid hormogenesis, is catalysed by the Na+/I- symporter, an intrinsic membrane protein that is crucial for the evaluation, diagnosis and treatment of thyroid disorders. Although several other important thyroid proteins involved in hormogenesis have been characterized, the Na+/I- symporter has not. Here we report the isolation of a complementary DNA clone that encodes this symporter, as a result of functional screening of a cDNA library from a rat thyroid-derived cell line (FRTL-5) in Xenopus laevis oocytes. Oocyte microinjection of an RNA transcript made in vitro from this cDNA clone elicited a more than 700-fold increase in perchlorate-sensitive Na+/I- symport activity over background. To our knowledge, this is the first iodide-transporting molecule to have its cDNA cloned, providing a missing link in the thyroid hormone biosynthetic pathway.
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