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Structural basis for partial agonist action at ionotropic glutamate receptors
Rongsheng Jin1, Tue G Banke, Mark L Mayer
1Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168 Street, New York, New York 10032, USA.
Nature Neuroscience
|July 23, 2003
Summary
Full and partial agonists activate neurotransmitter receptors differently. This study reveals how AMPA receptor partial agonists induce distinct conformational states, explaining varied responses at equal receptor occupancy.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Understanding neurotransmitter receptor function is crucial for pharmacology.
- Partial agonism mechanism remains unclear, with current models based on equilibrium shifts.
Purpose of the Study:
- To elucidate the structural basis of partial agonism in AMPA-subtype glutamate receptors.
- To explain how partial agonists yield different response amplitudes at equivalent receptor occupancy.
Main Methods:
- Crystallographic studies of the GluR2 receptor ligand-binding core.
- Electrophysiological recordings of ion channel activity.
- Utilized a series of 5-substituted willardiine partial agonists.
Main Results:
- The GluR2 ligand-binding core exhibits diverse ligand-dependent conformational states.
- These conformational states modulate the open probability of distinct ion channel subconductance states.
- Structural data provides a mechanism for partial agonism.
Conclusions:
- Partial agonism is mediated by ligand-induced conformational ensembles of the receptor.
- This provides a structure-based model for partial agonism in AMPA receptors.
- Findings advance the understanding of neurotransmitter receptor activation and drug action.