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Published on: June 9, 2017
The orphan GPR50 receptor specifically inhibits MT1 melatonin receptor function through heterodimerization
Angélique Levoye1, Julie Dam, Mohammed A Ayoub
1Department of Cell Biology, Institut Cochin, Paris, France.
The EMBO Journal
|June 17, 2006
Summary
GPR50, an orphan G protein-coupled receptor (GPCR), forms stable pairs with melatonin receptors MT(1) and MT(2). GPR50 inhibits MT(1) function by blocking ligand binding and G protein coupling.
Area of Science:
- Molecular and Cellular Biology
- Pharmacology
- Neuroscience
Background:
- G protein-coupled receptors (GPCRs) are crucial cell surface receptors involved in signal transduction.
- A significant portion of GPCRs remain 'orphan receptors' with unidentified ligands and functions.
- GPCRs can modulate each other's function through heterodimerization.
Purpose of the Study:
- To investigate the interaction between the orphan GPCR GPR50 and melatonin receptors MT(1) and MT(2).
- To determine the functional consequences of GPR50 heterodimerization with MT(1) and MT(2).
- To elucidate the role of the GPR50 C-terminal tail in regulating MT(1) function.
Main Methods:
- Biochemical and biophysical approaches in intact cells.
- Assessment of constitutive and specific heterodimerization between GPR50 and MT(1)/MT(2).
- Analysis of agonist binding affinity and G protein coupling to MT(1) in the presence of GPR50.
Main Results:
- GPR50 constitutively and specifically heterodimerizes with both MT(1) and MT(2) melatonin receptors.
- GPR50 binding to MT(2) did not alter MT(2) receptor function.
- GPR50 binding to MT(1) abolished high-affinity agonist binding and G protein coupling.
- Deletion of the GPR50 C-terminal tail abrogated the inhibitory effect on MT(1) without preventing heterodimerization.
Conclusions:
- GPR50 functions as a negative modulator of MT(1) receptor activity through its C-terminal domain.
- Heterodimerization between orphan GPCRs and known receptors offers a novel strategy to understand orphan receptor function.
- This interaction has potential clinical implications for modulating melatonin receptor signaling.
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