Table 4.
Relative potencies of thyroid hormone metabolites at thyroid hormone receptors expressed as fold concentration required to displace T3 from binding to TRβ1 which is set as 1 (in bold) (corresponding to a Kd = 1 × 10−10 nM).
| Receptor | T4 | T3 | rT3 | 3,5-T2 | Tetrac | Triac | References |
|---|---|---|---|---|---|---|---|
| TRα1 | 14 | 2–20 | – | – | – | 3.9 | (78) |
| TRβ1 | 3–22 | 1 | 300 | – | 33 | 3.6 | (79, 80) |
| TRβ2 | – | 32 | – | 40–500 | – | 4.2 | (81, 82) |
| pTRα28 | – | 3 | – | – | – | – | (83) |
| Integrin ανβ3 | 3 | – | – | – | – | – | (84) |
Published experimental data were obtained using various types of TH receptor preparations, Scatchard analyses or competition assays, resulting in IC-50 values. No systematic comparison was made using recombinantly expressed receptor under comparable binding conditions, ad different tissues, and species were used in competition experiments. Thus, only rough ranges are compiled here due to the limited comparability of experimental models.