Related Experiment Videos
Mutations at the GABA receptor selectivity filter: a possible role for effective charges
V E Wotring1, T S Miller, D S Weiss
1Department of Neurobiology, University of Alabama at Birmingham, 35294, USA.
The Journal of Physiology
|March 11, 2003
Summary
Investigating rho1 GABA receptors reveals that specific amino acid mutations alter ion selectivity. Charged residues near the pore
Area of Science:
- Neuroscience
- Molecular Biology
- Biophysics
Background:
- Ligand-gated ion channels exhibit remarkable ion selectivity, crucial for neuronal function.
- The structural basis for this selectivity in GABA receptors remains largely unknown.
Purpose of the Study:
- To elucidate the structural determinants of ionic selectivity in rho1 GABA receptors.
- To investigate the role of specific amino acid residues in controlling ion permeation.
Main Methods:
- Site-directed mutagenesis was employed to alter specific residues in rho1 GABA receptors.
- Electrophysiological techniques, including two-electrode voltage-clamp and patch-clamp, were used to measure ion permeability.
Main Results:
- Mutating alanine at position 291 to glutamate significantly reduced ion discrimination.
- Deleting proline at position 290 and mutating alanine at 291 reversed ion selectivity towards cations.
- Altering the charge of arginine at position 292 critically influenced cation permeability.
Conclusions:
- The effective charge near the intracellular mouth of the pore is a key determinant of rho1 GABA receptor ionic selectivity.
- Specific amino acid residues, particularly charged ones, play a critical role in modulating ion channel function.