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Functional characteristics of a variant thyrotropin receptor
M Tonacchera1, F Cetani, S Costagliola
1Institut de Recherche Interdisciplinaire, Faculté de Médicine, Université Libre de Bruxelles, Belgium.
European Journal of Biochemistry
|June 1, 1996
Summary
The [Thr52]thyrotropin receptor variant, found in 12% of the population, does not alter human thyrotropin receptor function. This variant is likely a simple polymorphism, not linked to autoimmune thyroid diseases.
Area of Science:
- Endocrinology
- Molecular Biology
- Genetics
Background:
- A variant of the human thyrotropin receptor, [Thr52]thyrotropin receptor, has been linked to autoimmune thyroid diseases.
- This variant is claimed to exhibit increased responsiveness to thyrotropin.
Purpose of the Study:
- To analyze the functional characteristics of the [Thr52]thyrotropin receptor variant.
- To determine if the [Thr52]thyrotropin receptor variant affects receptor function or is associated with disease.
Main Methods:
- Transient expression of wild-type and [Thr52]thyrotropin receptors in COS-7 cells.
- Measurement of receptor numbers via 125I-thyrotropin binding and flow cytometry.
- Analysis of constitutive activity and responsiveness to thyrotropin for cAMP and inositol-phosphate pathways.
Main Results:
- Both wild-type and [Thr52]thyrotropin receptors demonstrated equivalent constitutive activity for the cAMP pathway.
- The variant receptor exhibited the same affinity for bovine thyrotropin as the wild-type receptor.
- Responsiveness to bovine thyrotropin for both cAMP and inositol-phosphate pathways was virtually identical between the two receptor types.
Conclusions:
- The [Thr52]thyrotropin receptor variant does not affect human thyrotropin receptor function.
- Given its prevalence (12%) and lack of functional alteration, the [Thr52] variant is most likely a simple polymorphism.
- This finding suggests the variant is not a causative factor in autoimmune thyroid diseases.