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A Method to Study the C924T Polymorphism of the Thromboxane A2 Receptor Gene
Published on: April 1, 2019
Physiological significance of thromboxane A(2) receptor dimerization
Masako Sasaki1, Katsutoshi Miyosawa, Satoko Ohkubo
1Department of Cellular Signaling, Graduate School of Pharmaceutical Sciences, Tohoku University, Japan.
Journal of Pharmacological Sciences
|March 28, 2006
Summary
Thromboxane A(2) receptor (TP) variants TPalpha and TPbeta form dimers, influencing TP signaling. Dimerization affects cell surface expression and TP-mediated responses.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- The thromboxane A(2) receptor (TP) is a G protein-coupled receptor (GPCR) with two known splicing variants: TPalpha and TPbeta.
- These variants differ in their C-terminal regions, potentially affecting receptor function and localization.
Purpose of the Study:
- To investigate the homo- and hetero-dimerization of TPalpha and TPbeta.
- To determine if TP dimerization alters TP receptor function and cell surface expression.
Main Methods:
- Immunofluorescence analysis in human embryonic kidney (HEK) 293 cells to assess protein localization.
- Co-immunoprecipitation assays to detect TPalpha and TPbeta dimerization.
- Functional assays using Chinese hamster ovary (CHO) cells to measure phosphoinositide hydrolysis and intracellular calcium ([Ca(2+)](i)) elevation upon agonist stimulation.
- Radioligand binding assays using [(3)H]SQ29548 to quantify cell surface TP expression.
Main Results:
- TPalpha and TPbeta form both homo- and hetero-dimers.
- TPalpha is primarily localized to the plasma membrane, while TPbeta is found on both plasma membranes and intracellularly.
- Agonist-induced signaling (phosphoinositide hydrolysis and [Ca(2+)](i) elevation) was greater in cells expressing TPalpha compared to TPbeta.
- Cells expressing both TPalpha and TPbeta showed reduced U46619-induced responses compared to cells expressing TPalpha alone.
- Cell surface TP expression levels followed the order: TPalpha > TPalpha and TPbeta > TPbeta.
Conclusions:
- TPalpha and TPbeta variants can form homo- and hetero-dimers.
- TP dimerization influences TP receptor cell surface expression and modulates TP-mediated signaling pathways.
- Hetero-dimerization of TPalpha and TPbeta plays a role in regulating TP function.
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