A Direct Comparison of Thyroid Hormone Receptor Protein Levels in Mice Provides Unexpected Insights into Thyroid Hormone Action.

Thyroid hormone (TH) action is mediated by three major thyroid hormone receptor (THR) isoforms α1, β1, and β2 (THRA1, THRB1, and THRB2). These THRs and a fourth major but non-TH binding isoform, THRA2, are encoded by two genes and . Reliable antibodies against all THR isoforms are not available, and THR isoform protein levels in mammalian tissues are often inferred from messenger RNA (mRNA) levels.

Naturally Occurring Amino Acids in Helix 10 of the Thyroid Hormone Receptor Mediate Isoform-Specific TH Gene Regulation.

Thyroid hormone (TH) action is mediated by the products of two genes, TH receptor (THR)α (THRA) and THRβ (THRB) that encode several closely related receptor isoforms with differing tissue distributions. The vast majority of THR isoform-specific effects are thought to be due to tissue-specific differences in THR isoform expression levels. We investigated the alternative hypothesis that intrinsic functional differences among THR isoforms mediate these tissue-specific effects.