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Interaction of thyroid-hormone receptor with a conserved transcriptional mediator
J W Lee1, F Ryan, J C Swaffield
1Department of Molecular Biology, Wellman 9, Massachusetts General Hospital, Boston 02114.
Abstract:
The thyroid-hormone receptors are hormone-dependent transcription factors that control expression of many target genes. This regulation is presumably a consequence of hormone-dependent contacts between the receptors and the basal transcription machinery. We used the yeast two-hybrid system to identify a candidate human transcriptional mediator that interacts with both the thyroid-hormone receptor and the retinoid-X receptor in a ligand-dependent fashion. This protein, Trip1 (for thyroid-hormone-receptor interacting protein), shares striking sequence conservation with the yeast transcriptional mediator Sug1 (refs 6, 7). Here we show that Trip1 can functionally substitute for Sug1 in yeast, and that both proteins interact in vitro with the thyroid-hormone receptor, and with the transcriptional activation domains of yeast GAL4 and of herpes virus VP16.
Insights
Researchers identified Trip1, a human protein that interacts with thyroid-hormone receptors and retinoid-X receptors. Trip1 functions similarly to yeast mediator Sug1, highlighting conserved transcriptional regulation mechanisms.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Thyroid-hormone receptors are crucial transcription factors regulating gene expression.
- Hormone-dependent interactions between receptors and transcription machinery are key to this regulation.
Purpose of the Study:
- To identify human transcriptional mediators interacting with thyroid-hormone receptors.
- To characterize the function and interactions of a novel protein, Trip1.
Main Methods:
- Yeast two-hybrid system for identifying protein-protein interactions.
- In vitro binding assays to confirm interactions.
Main Results:
- Identified Trip1 (thyroid-hormone-receptor interacting protein) as a human mediator.
- Trip1 interacts with thyroid-hormone receptors and retinoid-X receptors in a ligand-dependent manner.
- Trip1 functionally substitutes for yeast mediator Sug1 and interacts with the thyroid-hormone receptor.
Conclusions:
- Trip1 is a conserved transcriptional mediator involved in thyroid hormone signaling.
- Ligand-dependent interactions mediated by proteins like Trip1 are essential for regulating gene expression.