Type 2 iodothyronine deiodinase is the major source of plasma T₃ in euthyroid humans
J. Clin. Invest. Ana Luiza Maia, et al. 115:2524 doi:10.1172/JCI25083 [Go to this article.]

Figure 1
Model for quantification of T₃ production in cells transiently expressing D1 or D2. (A) Distribution of [¹²⁵I]T₃, [¹²⁵I]T₄, and I^– in HEK 293 cells incubated in 0.1% BSA medium for 22 hours. (B–H) Cells were transfected with 3–100 ng of D1- or D2-expressing plasmids and incubated for 22 hours in 1 ml 0.1% BSA DMEM, to which were added the indicated concentrations of T₄, including approximately 100,000 cpm/ml of [¹²⁵I]T₄. Whole-cell T₄ to T₃ conversion rates were determined from the fraction of [¹²⁵I]T₄ appearing as ¹²⁵I^–. The Vmax for each deiodinase was determined in cell sonicates, harvested after completion of the incubation. (B) Fractional T₄ deiodination over time. (C) Correlation between the quantity of plasmid transfected and fractional deiodination. (D) Correlation between Vmax and fractional deiodination. (E) D1 and D2 Vmax versus the quantity of plasmid transfected. (F) Time course of transient deiodinase expression over 72 hours. Effect of PTU (G) or T₄ (H) on fractional T₄ deiodination in D1- and D2-expressing cells. All data are expressed as the mean of duplicate samples in 3 independent experiments.