Related Experiment Videos
Differences in nuclear thyroid hormone receptors among species.
K Ichikawa1, K Hashizume, T Miyamoto
1Department of Gerontology, Endocrinology, and Metabolism, Shinshu University School of Medicine, Matsumoto, Japan.
General and Comparative Endocrinology
|April 1, 1989
Summary
Comparing thyroid hormone receptors across species reveals significant structural differences. While rat, dog, and chicken receptors show similar T3 affinities, rainbow trout receptors exhibit lower affinity and distinct DNA binding properties.
Area of Science:
- Comparative endocrinology
- Molecular biology
- Biochemistry
Background:
- Thyroid hormones regulate metabolism and development across vertebrates.
- Nuclear thyroid hormone receptors (TRs) mediate these effects.
- Understanding TR structure and function across species is crucial for evolutionary and physiological insights.
Purpose of the Study:
- To compare hepatic nuclear thyroid hormone receptors from rat, dog, chicken, and rainbow trout.
- To investigate species-specific differences in T3 binding affinity, nuclear release, DNA interaction, and structural characteristics.
Main Methods:
- Isolation and extraction of hepatic nuclear receptors.
- Binding assays to determine T3 affinity.
- Incubation of isolated nuclei to assess receptor release.
- DNA-cellulose chromatography for receptor-DNA interaction analysis.
- Sephacryl S-200 chromatography for Stokes radius determination.
- Partial proteolysis to analyze T3-binding fragments.
Main Results:
- Receptor affinities for T3 were similar in rat, dog, and chicken, but lower in rainbow trout.
- Significant differences in receptor-DNA interactions were observed, with dog and rainbow trout receptors showing similarities.
- Chicken TRs had a smaller Stokes radius than rat TRs.
- Partial proteolysis yielded distinct T3-binding fragments across species, indicating structural variations.
Conclusions:
- Hepatic nuclear thyroid hormone receptors exhibit significant structural dissimilarities among different species.
- These structural variations likely contribute to species-specific regulation of thyroid hormone action.
- Comparative analysis provides insights into the evolution of thyroid hormone signaling pathways.