Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Coupling of agonist binding to channel gating in the GABAA receptor


Neurotransmitters such as acetylcholine and GABA (γ-aminobutyric acid) mediate rapid synaptic transmission by activating receptors belonging to the gene superfamily of ligand-gated ion channels (LGICs)1. These channels are pentameric proteins that function as signal transducers, converting chemical messages into electrical signals2. Neurotransmitters activate LGICs by interacting with a ligand-binding site3,4,5,6,7, triggering a conformational change in the protein that results in the opening of an ion channel8. This process, which is known as ‘gating’, occurs rapidly and reversibly, but the molecular rearrangements involved are not well understood9. Here we show that optimal gating in the GABAA receptor, a member of the LGIC superfamily, is dependent on electrostatic interactions between the negatively charged Asp 57 and Asp 149 residues in extracellular loops 2 and 7, and the positively charged Lys 279 residue in the transmembrane 2–3 linker region of the α1-subunit. During gating, Asp 149 and Lys 279 seem to move closer to one another, providing a potential mechanism for the coupling of ligand binding to opening of the ion channel.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Charge exchange between positions 149 and 279 restores optimal GABA sensitivity.
Figure 2: Mutant cycle analysis and disulphide crosslinking experiments support interactions between loops 2 and 7 and the 2–3L region.
Figure 3: Molecular model of the GABAA-R α1 subunit.


  1. Schofield, P. R. et al. Sequence and functional expression of the GABAA receptor shows a ligand-gated receptor super-family. Nature 328, 221–227 (1987)

    ADS  CAS  Article  Google Scholar 

  2. Betz, H. Ligand-gated ion channels in the brain: the amino acid receptor superfamily. Neuron 5, 383–392 (1990)

    CAS  Article  Google Scholar 

  3. Karlin, A. Emerging structure of the nicotinic acetylcholine receptors. Nature Rev. Neurosci. 3, 102–114 (2002)

    CAS  Article  Google Scholar 

  4. Brejc, K. et al. Crystal structure of an ACh-binding protein reveals the ligand-binding domain of nicotinic receptors. Nature 411, 269–276 (2001)

    ADS  CAS  Article  Google Scholar 

  5. Smith, G. B. & Olsen, R. W. Identification of a [3H]muscimol photoaffinity substrate in the bovine γ-aminobutyric acidA receptor α subunit. J. Biol. Chem. 269, 20380–20387 (1994)

    CAS  Google Scholar 

  6. Sigel, E., Baur, R., Kellenberger, S. & Malherbe, P. Point mutations affecting antagonist affinity and agonist dependent gating of GABAA receptor channels. EMBO J. 11, 2017–2023 (1992)

    CAS  Article  Google Scholar 

  7. Boileau, A. J., Evers, A. R., Davis, A. F. & Czajkowski, C. Mapping the agonist binding site of the GABAA receptor: evidence for a β-strand. J. Neurosci. 19, 4847–4854 (1999)

    CAS  Article  Google Scholar 

  8. Grosman, C., Zhou, M. & Auerbach, A. Mapping the conformational wave of acetylcholine receptor channel gating. Nature 403, 773–776 (2000)

    ADS  CAS  Article  Google Scholar 

  9. Dougherty, D. A. & Lester, H. A. Neurobiology. Snails, synapses and smokers. Nature 411, 252–253 (2001)

    ADS  CAS  Article  Google Scholar 

  10. Croxen, R. C. et al. Mutations in different functional domains of the human muscle acetylcholine receptor α subunit in patients with the slow-channel congenital myasthenic syndrome. Hum. Mol. Genet. 6, 767–774 (1997)

    CAS  Article  Google Scholar 

  11. Shiang, R. et al. Mutations in the α1 subunit of the inhibitory glycine receptor cause the dominant neurologic disorder, hyperekplexia. Nature Genet. 4, 351–358 (1993)

    Article  Google Scholar 

  12. Baulac, S. et al. First genetic evidence of GABAA receptor dysfunction in epilepsy: mutation in the γ2-subunit gene. Nature Genet. 28, 46–48 (2001)

    CAS  Google Scholar 

  13. O'Shea, S. M. & Harrison, N. L. Arg-274 and Leu-277 of the γ-aminobutyric acid type A receptor α2 subunit define agonist efficacy and potency. J. Biol. Chem. 275, 22764–22768 (2000)

    CAS  Article  Google Scholar 

  14. Sigel, E., Buhr, A. & Baur, R. Role of the conserved lysine residue in the middle of the predicted extra-cellular loop between M2 and M3 in the GABAA receptor. J. Neurochem. 73, 1758–1764 (1999)

    CAS  Article  Google Scholar 

  15. Ebert, B. et al. Differences in agonist/antagonist binding affinity and receptor transduction using recombinant human γ-aminobutyric acid type A receptors. Mol. Pharmacol. 52, 1150–1156 (1997)

    CAS  Article  Google Scholar 

  16. Steinbach, J. H. & Akk, G. Modulation of GABAA receptor channel gating by pentobarbital. J. Physiol. (Lond.) 537, 715–733 (2001)

    CAS  Article  Google Scholar 

  17. Carter, P. J., Winter, G., Wilkinson, A. J. & Fersht, A. R. The use of double mutants to detect structural changes in the active site of the tyrosyl-tRNA synthetase (Bacillus stearothermophilus). Cell 38, 835–840 (1984)

    CAS  Article  Google Scholar 

  18. Hidalgo, P. & MacKinnon, R. Revealing the architecture of a K+ channel pore through mutant cycles with a peptide inhibitor. Science 268, 307–310 (1995)

    ADS  CAS  Article  Google Scholar 

  19. Schreiber, G. & Fersht, A. R. Energetics of protein–protein interactions: analysis of the barnase–barstar interface by single mutations and double mutant cycles. J. Mol. Biol. 248, 478–486 (1995)

    CAS  Google Scholar 

  20. DiPaola, M., Czajkowski, C. & Karlin, A. The sidedness of the COOH terminus of the acetylcholine receptor δ subunit. J. Biol. Chem. 264, 15457–15463 (1989)

    CAS  Google Scholar 

  21. Horenstein, J., Wagner, D. A., Czajkowski, C. & Akabas, M. H. Protein mobility and GABA-induced conformational changes in GABAA receptor pore-lining M2 segment. Nature Neurosci. 4, 477–485 (2001)

    CAS  Article  Google Scholar 

  22. Thornton, J. M. Disulphide bridges in globular proteins. J. Mol. Biol. 151, 261–287 (1981)

    CAS  Article  Google Scholar 

  23. Bertaccini, E. & Trudell, J. R. Predicting the transmembrane secondary structure of ligand-gated ion channels. Protein Eng. 15, 443–454 (2002)

    CAS  Article  Google Scholar 

  24. Unwin, N., Miyazawa, A., Li, J. & Fujiyoshi, Y. Activation of the nicotinic acetylcholine receptor involves a switch in conformation of the α subunits. J. Mol. Biol. 319, 1165–1176 (2002)

    CAS  Article  Google Scholar 

  25. Nishikawa, K., Jenkins, A., Paraskevakis, I. & Harrison, N. L. Volatile anesthetic actions on the GABAA receptors: contrasting effects of α1(S270) and β2(N265) point mutations. Neuropharmacology 42, 337–345 (2002)

    CAS  Article  Google Scholar 

  26. Trudell, J. Unique assignment of inter-subunit association in GABAA α1β3γ2 receptors determined by molecular modelling. Biochim. Biophys. Acta 1565, 91–96 (2002)

    CAS  Article  Google Scholar 

  27. Trudell, J. R. & Bertaccini, E. Molecular modelling of specific and non-specific anaesthetic interactions. Br. J. Anaesth. 89, 32–40 (2002)

    CAS  Article  Google Scholar 

  28. Bera, M., Chatav, M. & Akabas, M. GABA(A) receptor M2-3 loop secondary structure and changes in accessibility during channel gating. J. Biol. Chem. 277, 43002–43010 (2002)

    CAS  Article  Google Scholar 

Download references


We thank J. Horenstein for advice on crosslinking experiments and the NIH for financial support.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Neil L. Harrison.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kash, T., Jenkins, A., Kelley, J. et al. Coupling of agonist binding to channel gating in the GABAA receptor. Nature 421, 272–275 (2003).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing